CMake: fix AUDASPACE disabling WITH_PYTHON for Blender

When AUDASPACE couldn't find NUMPY, it would disable WITH_PYTHON for
the rest of Blender. Now setting the value globally is only done for
standalone AUDASPACE builds. Now it's possible to build Blender with
AUDASPACE & PYTHON but without NUMPY.

While this isn't an especially important configuration to support,
having Python mysteriously disabled is a hassle to troubleshoot.

NOTE: extern/audaspace/CMakeLists.txt has become out sync with the
original [0], it seems this is being maintained in our repository.

[0]: https://github.com/neXyon/audaspace/blob/master/CMakeLists.txt

source/blender/python/intern/bpy_interface.c

@@ -238,7 +238,7 @@ void BPY_context_set(bContext *C)
 extern PyObject *Manta_initPython(void);
 #endif
 
-#ifdef WITH_AUDASPACE
+#ifdef WITH_AUDASPACE_PY
 /* defined in AUD_C-API.cpp */
 extern PyObject *AUD_initPython(void);
 #endif
@@ -272,7 +272,7 @@ static struct _inittab bpy_internal_modules[] = {
 #ifdef WITH_FLUID
     {"manta", Manta_initPython},
 #endif
-#ifdef WITH_AUDASPACE
+#ifdef WITH_AUDASPACE_PY
     {"aud", AUD_initPython},
 #endif
 #ifdef WITH_CYCLES