Add MAKEPANDA defsymbol to export module init function as initlibp3dtoolconfig instead of initlibdtoolconfig

dtool/metalibs/dtoolconfig/pydtool.cxx

@@ -2074,6 +2074,20 @@ static PyMethodDef python_simple_funcs[] = {
   { NULL, NULL }
 };
 
+// Makepanda builds the library as libp3dtoolconfig instead of libdtoolconfig.
+#ifdef MAKEPANDA
+#ifdef _WIN32
+extern "C" __declspec(dllexport) void initlibp3dtoolconfig();
+#else
+extern "C" void initlibp3dtoolconfig();
+#endif
+
+void initlibp3dtoolconfig() {
+  Py_InitModule("libp3dtoolconfig", python_simple_funcs);
+}
+
+#else  // MAKEPANDA
+
 #ifdef _WIN32
 extern "C" __declspec(dllexport) void initlibdtoolconfig();
 #else
@@ -2083,4 +2097,5 @@ extern "C" void initlibdtoolconfig();
 void initlibdtoolconfig() {
   Py_InitModule("libdtoolconfig", python_simple_funcs);
 }
+#endif  // MAKEPANDA
 

makepanda/makepanda.py

@@ -518,6 +518,7 @@ if (COMPILER=="LINUX"):
             if (sys.platform == "darwin"):
                 LibName(pkg, "-dylib_file /System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib")
 
+DefSymbol("ALWAYS", "MAKEPANDA", "")
 DefSymbol("WITHINPANDA", "WITHIN_PANDA", "1")
 IncDirectory("ALWAYS", GetOutputDir()+"/tmp")
 IncDirectory("ALWAYS", GetOutputDir()+"/include")