Skip libdispatch detection on darwin

Author: Oleksiy-Yakovenko

configure.ac

@@ -271,9 +271,15 @@ AS_IF([test "${enable_staticlink}" != "no"], [
     AC_CHECK_LIB([dispatch], [main], [HAVE_DISPATCH=yes])
 ])
 
-AC_CHECK_LIB([dispatch], [main], [], [
-    AC_MSG_ERROR([libdispatch not found. Please install libdispatch.])
-])
+AS_CASE([$host_os],
+ [darwin*], [
+    AC_MSG_NOTICE([Skipping libdispatch check on macOS])
+  ],
+  [
+    AC_CHECK_LIB([dispatch], [main], [], [
+      AC_MSG_ERROR([libdispatch not found. Please install libdispatch.])
+    ])
+  ])
 DISPATCH_CFLAGS=-fblocks
 DISPATCH_LIBS="-ldispatch -lBlocksRuntime"
 AC_SUBST(DISPATCH_CFLAGS)