ruby gem cannot be compiled on OS X mavericks

You get

In file included from strlcpy.c:20:
./strlcpy.h:28:15: error: expected parameter declarator
extern size_t strlcpy(char *, const char *, size_t);
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/secure/_string.h:105:44: note: expanded from macro 'strlcpy'
_builtin__strlcpy_chk (dest, src, len, __darwin_obsz (dest))
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/secure/common.h:39:62: note: expanded from macro '_darwin_obsz'
#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/secure/_common.h:30:32: note: expanded from macro '_USE_FORTIFY_LEVEL'

1. define _USE_FORTIFY_LEVEL 2
   ^

It seems to me that since you're including string.h, you shouldn't declare your own extern for strlcpy, since it might differ in parameter decorators or linkage type or something.

This affects both 0.8.0 and 0.9.1 that I have tried