meson: Don't check for posix_memalign on windows

There's a mingw bug for this, it exports __builtin_posix_memalign but
not posix_memalign, so the check will succeed, but compiling will fail.

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Acked-by: Kristian H. Kristensen <hoegsberg@google.com>
diff --git a/meson.build b/meson.build
index 8c5ae52..824765e 100644
--- a/meson.build
+++ b/meson.build
@@ -1145,7 +1145,7 @@
   endif
 endforeach
 
-foreach f : ['strtof', 'mkostemp', 'posix_memalign', 'timespec_get', 'memfd_create', 'random_r']
+foreach f : ['strtof', 'mkostemp', 'timespec_get', 'memfd_create', 'random_r']
   if cc.has_function(f)
     pre_args += '-DHAVE_@0@'.format(f.to_upper())
   endif
@@ -1158,6 +1158,16 @@
   error('Intel tools require the program_invocation_name variable')
 endif
 
+# MinGW provides a __builtin_posix_memalign function, but not a posix_memalign.
+# This means that this check will succeed, but then compilation will later
+# fail. MSVC doesn't have this function at all, so only check for it on
+# non-windows platforms.
+if host_machine.system() != 'windows'
+  if cc.has_function('posix_memalign')
+    pre_args += '-DHAVE_POSIX_MEMALIGN'
+  endif
+endif
+
 # strtod locale support
 if cc.links('''
     #define _GNU_SOURCE