fnmatch-gnu fails to compile on OSX with clang

[Jeroen Meijer]

It seems that the recent changes related to fnmatch breaks builds on OSX.

I tested on Travis CI, with Xcode 9.4 (clang-902).

The compiler error I get is the following:

/bin/sh ../libtool  --tag=CC   --mode=compile clang -DHAVE_CONFIG_H -I. 
-I../src/hre     -g -O2 -W -Wall -pipe -c -o fnmatch.lo fnmatch.c
libtool: compile:  clang -DHAVE_CONFIG_H -I. -I../src/hre -g -O2 -W 
-Wall -pipe -c fnmatch.c -o fnmatch.o
In file included from fnmatch.c:176:
./fnmatch_loop.c:49:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^
./fnmatch_loop.c:81:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^
./fnmatch_loop.c:96:45: error: use of undeclared identifier 'FNM_EXTMATCH'
              if (*p == L_('(') && (flags & FNM_EXTMATCH) != 0)
                                            ^
./fnmatch_loop.c:157:49: error: use of undeclared identifier 'FNM_EXTMATCH'
                  || (__builtin_expect (flags & FNM_EXTMATCH, 0) != 0
                                                ^
./fnmatch_loop.c:944:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^
In file included from fnmatch.c:272:
./fnmatch_loop.c:49:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^
./fnmatch_loop.c:81:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^
./fnmatch_loop.c:96:45: error: use of undeclared identifier 'FNM_EXTMATCH'
              if (*p == L_('(') && (flags & FNM_EXTMATCH) != 0)
                                            ^
./fnmatch_loop.c:157:49: error: use of undeclared identifier 'FNM_EXTMATCH'
                  || (__builtin_expect (flags & FNM_EXTMATCH, 0) != 0
                                                ^
./fnmatch_loop.c:944:41: error: use of undeclared identifier 'FNM_EXTMATCH'
          if (__builtin_expect (flags & FNM_EXTMATCH, 0) && *p == '(')
                                        ^