Looks like an API incompatibility with the latest version of OpenJPEG as MuPDF builds fine against the 1.5 release. Errors occur when building image_jpx.o and possible other files:


    CC build/debug/image_jpx.o
fitz/image_jpx.c:27:2: error: use of undeclared identifier 'opj_event_mgr_t'
        opj_event_mgr_t evtmgr;
        ^
fitz/image_jpx.c:29:2: error: unknown type name 'opj_dinfo_t'; did you mean 'opj_tp_info_t'?
        opj_dinfo_t *info;
        ^~~~~~~~~~~
        opj_tp_info_t
/usr/local/include/openjpeg-2.0/openjpeg.h:637:3: note: 'opj_tp_info_t' declared here
} opj_tp_info_t;
  ^
fitz/image_jpx.c:30:2: error: unknown type name 'opj_cio_t'; did you mean 'opj_poc_t'?
        opj_cio_t *cio;
        ^~~~~~~~~
        opj_poc_t
/usr/local/include/openjpeg-2.0/openjpeg.h:254:3: note: 'opj_poc_t' declared here
} opj_poc_t;
  ^
fitz/image_jpx.c:43:12: error: use of undeclared identifier 'CODEC_J2K'
                format = CODEC_J2K;
                         ^
fitz/image_jpx.c:45:12: error: use of undeclared identifier 'CODEC_JP2'
                format = CODEC_JP2;
                         ^
fitz/image_jpx.c:47:10: error: use of undeclared identifier 'evtmgr'
        memset(&evtmgr, 0, sizeof(evtmgr));
                ^
/usr/include/secure/_string.h:76:21: note: expanded from macro 'memset'
  ((__darwin_obsz0 (dest) != (size_t) -1)                               \
                    ^
/usr/include/secure/_common.h:38:55: note: expanded from macro '__darwin_obsz0'
#define __darwin_obsz0(object) __builtin_object_size (object, 0)
                                                      ^
fitz/image_jpx.c:47:10: error: use of undeclared identifier 'evtmgr'
        memset(&evtmgr, 0, sizeof(evtmgr));
                ^
/usr/include/secure/_string.h:77:30: note: expanded from macro 'memset'
   ? __builtin___memset_chk (dest, val, len, __darwin_obsz0 (dest))     \
                             ^
fitz/image_jpx.c:47:10: error: use of undeclared identifier 'evtmgr'
        memset(&evtmgr, 0, sizeof(evtmgr));
                ^
/usr/include/secure/_string.h:78:27: note: expanded from macro 'memset'
   : __inline_memset_chk (dest, val, len))
                          ^
fitz/image_jpx.c:48:2: error: use of undeclared identifier 'evtmgr'
        evtmgr.error_handler = fz_opj_error_callback;
        ^
fitz/image_jpx.c:49:2: error: use of undeclared identifier 'evtmgr'
        evtmgr.warning_handler = fz_opj_warning_callback;
        ^
fitz/image_jpx.c:50:2: error: use of undeclared identifier 'evtmgr'
        evtmgr.info_handler = fz_opj_info_callback;
        ^
fitz/image_jpx.c:56:7: warning: incompatible pointer types assigning to 'opj_tp_info_t *'
      (aka 'struct opj_tp_info *') from 'opj_codec_t *' (aka 'void **')
      [-Wincompatible-pointer-types]
        info = opj_create_decompress(format);
             ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fitz/image_jpx.c:57:2: warning: implicit declaration of function 'opj_set_event_mgr' is invalid
      in C99 [-Wimplicit-function-declaration]
        opj_set_event_mgr((opj_common_ptr)info, &evtmgr, ctx);
        ^
fitz/image_jpx.c:57:21: error: use of undeclared identifier 'opj_common_ptr'
        opj_set_event_mgr((opj_common_ptr)info, &evtmgr, ctx);
                           ^
fitz/image_jpx.c:58:20: warning: incompatible pointer types passing 'opj_tp_info_t *'
      (aka 'struct opj_tp_info *') to parameter of type 'opj_codec_t *' (aka 'void **')
      [-Wincompatible-pointer-types]
        opj_setup_decoder(info, &params);
                          ^~~~
/usr/local/include/openjpeg-2.0/openjpeg.h:1140:62: note: passing argument to parameter
      'p_codec' here
OPJ_API OPJ_BOOL OPJ_CALLCONV opj_setup_decoder(opj_codec_t *p_codec,
                                                             ^
fitz/image_jpx.c:60:8: warning: implicit declaration of function 'opj_cio_open' is invalid in
      C99 [-Wimplicit-function-declaration]
        cio = opj_cio_open((opj_common_ptr)info, data, size);
              ^
fitz/image_jpx.c:60:22: error: use of undeclared identifier 'opj_common_ptr'
        cio = opj_cio_open((opj_common_ptr)info, data, size);
                            ^
fitz/image_jpx.c:62:28: error: too few arguments to function call, expected 3, have 2
        jpx = opj_decode(info, cio);
              ~~~~~~~~~~          ^
/usr/local/include/openjpeg-2.0/openjpeg.h:1181:1: note: 'opj_decode' declared here
OPJ_API OPJ_BOOL OPJ_CALLCONV opj_decode(   opj_codec_t *p_decompressor,
^
/usr/local/include/openjpeg-2.0/openjpeg.h:59:20: note: expanded from macro 'OPJ_API'
#define OPJ_API    __attribute__ ((visibility ("default")))
                   ^
fitz/image_jpx.c:64:2: warning: implicit declaration of function 'opj_cio_close' is invalid in
      C99 [-Wimplicit-function-declaration]
        opj_cio_close(cio);
        ^
fitz/image_jpx.c:65:2: warning: implicit declaration of function 'opj_destroy_decompress' is
      invalid in C99 [-Wimplicit-function-declaration]
        opj_destroy_decompress(info);
        ^
fitz/image_jpx.c:95:26: error: use of undeclared identifier 'CLRSPC_SRGB'
        if (jpx->color_space == CLRSPC_SRGB && n == 4) { n = 3; a = 1; }
                                ^
fitz/image_jpx.c:96:31: error: use of undeclared identifier 'CLRSPC_SYCC'
        else if (jpx->color_space == CLRSPC_SYCC && n == 4) { n = 3; a = 1; }
                                     ^
6 warnings and 16 errors generated.
make: *** [build/debug/image_jpx.o] Error 1