getline: split out for darwin systems

At least on OS X 10.5 and older, getline does not exist.  So split out the
function from the mingw code so that we can pull it in for Darwin systems.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/tools/os_support.c b/tools/os_support.c
index 5b919aa..1ed89e6 100644
--- a/tools/os_support.c
+++ b/tools/os_support.c
@@ -23,3 +23,6 @@
 #ifdef __MINGW32__
 #include "mingw_support.c"
 #endif
+#ifdef __APPLE__
+#include "getline.c"
+#endif