$ make
cc -g -O2  -I. -I./LZMA/lzma465/C -I./LZMA/lzmalt -I./LZMA/lzmadaptive/C/7zip/Compress/LZMA_Lib -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_GNU_SOURCE -DCOMP_DEFAULT=\"gzip\" -Wall -Werror  -DGZIP_SUPPORT -DLZMA_SUPPORT -DXZ_SUPPORT -DLZO_SUPPORT -DXATTR_SUPPORT -DXATTR_DEFAULT   -c -o unsquashfs.o unsquashfs.c
In file included from unsquashfs.c:26:0:
unsquashfs.h:51:0: error: "__BYTE_ORDER" redefined [-Werror]
 #define __BYTE_ORDER BYTE_ORDER

In file included from /usr/include/machine/_endian.h:14:0,
                 from /usr/include/machine/endian.h:6,
                 from /usr/include/sys/types.h:67,
                 from /usr/include/stdio.h:61,
                 from unsquashfs.h:29,
                 from unsquashfs.c:26:
/usr/include/bits/endian.h:20:0: note: this is the location of the previous definition
 # define __BYTE_ORDER __LITTLE_ENDIAN

In file included from unsquashfs.c:26:0:
unsquashfs.h:52:0: error: "__BIG_ENDIAN" redefined [-Werror]
 #define __BIG_ENDIAN BIG_ENDIAN

In file included from /usr/include/machine/_endian.h:14:0,
                 from /usr/include/machine/endian.h:6,
                 from /usr/include/sys/types.h:67,
                 from /usr/include/stdio.h:61,
                 from unsquashfs.h:29,
                 from unsquashfs.c:26:
/usr/include/bits/endian.h:13:0: note: this is the location of the previous definition
 # define __BIG_ENDIAN 4321

In file included from unsquashfs.c:26:0:
unsquashfs.h:53:0: error: "__LITTLE_ENDIAN" redefined [-Werror]
 #define __LITTLE_ENDIAN LITTLE_ENDIAN

In file included from /usr/include/machine/_endian.h:14:0,
                 from /usr/include/machine/endian.h:6,
                 from /usr/include/sys/types.h:67,
                 from /usr/include/stdio.h:61,
                 from unsquashfs.h:29,
                 from unsquashfs.c:26:
/usr/include/bits/endian.h:16:0: note: this is the location of the previous definition
 # define __LITTLE_ENDIAN 1234

unsquashfs.c: In function ‘matches’:
unsquashfs.c:1443:35: error: ‘FNM_EXTMATCH’ undeclared (first use in this function)
     name, FNM_PATHNAME|FNM_PERIOD|FNM_EXTMATCH) ==
                                   ^~~~~~~~~~~~
unsquashfs.c:1443:35: note: each undeclared identifier is reported only once for each function it appears in
unsquashfs.c: In function ‘initialise_threads’:
unsquashfs.c:2299:12: error: ‘CTL_HW’ undeclared (first use in this function)
   mib[0] = CTL_HW;
            ^~~~~~
unsquashfs.c:2303:12: error: ‘HW_NCPU’ undeclared (first use in this function)
   mib[1] = HW_NCPU;
            ^~~~~~~
unsquashfs.c:2306:6: error: implicit declaration of function ‘sysctl’ [-Werror=implicit-function-declaration]
   if(sysctl(mib, 2, &processors, &len, NULL, 0) == -1) {
      ^~~~~~
cc1: all warnings being treated as errors
make: *** [<builtin>: unsquashfs.o] Error 1