Add new DISTRHO_NO_WARNINGS macro, use it on macOS test builds

.travis/script-macos.sh

@@ -3,7 +3,7 @@
 set -e
 
 # Preparation
-_FLAGS="-Werror"
+_FLAGS="-DDISTRHO_NO_WARNINGS -Werror"
 export CFLAGS="${_FLAGS}"
 export CXXFLAGS="${_FLAGS}"
 export MACOS_OLD=true

distrho/src/DistrhoPluginLADSPA+DSSI.cpp

@@ -30,12 +30,12 @@
 # if DISTRHO_PLUGIN_WANT_MIDI_INPUT || DISTRHO_PLUGIN_WANT_MIDI_OUTPUT
 #  error Cannot use MIDI with LADSPA
 # endif
-# if DISTRHO_PLUGIN_WANT_STATE
+# if DISTRHO_PLUGIN_WANT_STATE && !defined(DISTRHO_NO_WARNINGS)
 #  warning LADSPA cannot handle states
 # endif
 #endif
 
-#if DISTRHO_PLUGIN_WANT_TIMEPOS
+#if DISTRHO_PLUGIN_WANT_TIMEPOS && !defined(DISTRHO_NO_WARNINGS)
 # warning LADSPA/DSSI does not support TimePos
 #endif
 

distrho/src/DistrhoPluginVST.cpp

@@ -405,7 +405,9 @@ public:
 #  ifdef __LP64__
         fUsingNsView = true;
 #  else
-#   warning 32bit VST UIs on OSX only work if the host supports "hasCockosViewAsConfig"
+#   ifndef DISTRHO_NO_WARNINGS
+#    warning 32bit VST UIs on OSX only work if the host supports "hasCockosViewAsConfig"
+#   endif
         fUsingNsView = false;
 #  endif
 # endif // DISTRHO_OS_MAC