eina: add includes for getpid() to work on MacOSX

Without this I get errors from the clang compiler used on Travis for some OSX
builds:
../src/lib/eina/eina_inline_lock_posix.x:845:27: error: use of undeclared identifier 'getpid'

src/lib/eina/eina_inline_lock_posix.x

@@ -49,6 +49,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <sys/types.h>
+#include <unistd.h>
+
 #ifdef EINA_HAVE_DEBUG_THREADS
 #include <assert.h>
 #include <execinfo.h>