SL-821: Add -fmodules to llappdelegate-objc.mm compile switches.

The BugsplatMac package is built as a module requiring @import. Using @import
requires Objective-C++ module support, which requires the -fmodules switch.

indra/newview/CMakeLists.txt

@@ -1361,6 +1361,7 @@ if (DARWIN)
     llappdelegate-objc.mm
     PROPERTIES
     COMPILE_DEFINITIONS "${VIEWER_CHANNEL_VERSION_DEFINES}"
+    COMPILE_FLAGS "-fmodules"
     )
 
   find_library(AGL_LIBRARY AGL)