Since bump to ghostscript 9.27, we have some build failures on our buildroot autobuilders: http://autobuild.buildroot.org/?reason=ghostscript-9.27

I think those build failures are parallel build issues, ghostscript tries to build gsmd5.c but does not find arch.h:

/home/buildroot/buildroot-test/instance-1/output/host/bin/sh4-linux-gcc  -DHAVE_MKSTEMP -DHAVE_FILE64 -DHAVE_FSEEKO -DHAVE_MKSTEMP64 -DHAVE_FONTCONFIG  -DHAVE_SETLOCALE   -DHAVE_BSWAP32 -DHAVE_BYTESWAP_H -DHAVE_STRERROR -DHAVE_ISNAN   -DHAVE_PREAD_PWRITE=1 -DGS_RECURSIVE_MUTEXATTR=PTHREAD_MUTEX_RECURSIVE -O2 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Wall -Wstrict-prototypes -Wundef -Wmissing-declarations -Wmissing-prototypes -Wwrite-strings -fno-strict-aliasing -Werror=declaration-after-statement -fno-builtin -fno-common -Werror=return-type -DHAVE_STDINT_H=1 -DHAVE_DIRENT_H=1 -DHAVE_SYS_DIR_H=1 -DHAVE_SYS_TIME_H=1 -DHAVE_SYS_TIMES_H=1 -DHAVE_INTTYPES_H=1 -DHAVE_LIBDL=1 -DGX_COLOR_INDEX_TYPE="unsigned long long" -D__USE_UNIX98=1  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os   -DHAVE_RESTRICT=1 -fno-strict-aliasing -DHAVE_POPEN_PROTO=1    -I./obj -I./base -I./devices  -DWHICH_CMS="lcms2" -o ./obj/gsmd5.o -c ./obj/gsmd5.c
./obj/aux/echogs -a ./obj/gconfig_.h
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 ifndef HAVE_SYS_NDIR_H
if ( test -f /usr/include/sys/ndir.h ); then ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_NDIR_H 1; \
              else ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_NDIR_H 0; fi
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 endif
./obj/aux/echogs -a ./obj/gconfig_.h
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 ifndef HAVE_SYS_TIME_H
if ( test -f /usr/include/sys/time.h ); then ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_TIME_H 1; \
              else ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_TIME_H 0; fi
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 endif
./obj/aux/echogs -a ./obj/gconfig_.h
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 ifndef HAVE_SYS_TIMES_H
if ( test -f /usr/include/sys/times.h ); then ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_TIMES_H 1; \
              else ./obj/aux/echogs -a ./obj/gconfig_.h -x 23 define HAVE_SYS_TIMES_H 0; fi
./obj/aux/echogs -a ./obj/gconfig_.h -x 23 endif
In file included from ./base/memory_.h:23:0,
                 from ./obj/gsmd5.h:1,
                 from ./obj/gsmd5.c:56:
./base/std.h:25:10: fatal error: arch.h: No such file or directory
 #include "arch.h"
          ^~~~~~~~
compilation terminated.

I think that this issue has been added with http://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=26657b796bb6756bf5a907f1745efe1d325978e0, base/lib.mak should be updated to be sure that arch.h is built before gsmd5.c is compiled