Update to latest emscripten toolchain

Corrected issue on web compilation

src/Makefile

@@ -150,7 +150,7 @@ ifeq ($(PLATFORM),PLATFORM_WEB)
     EMSDK_PATH         ?= C:/emsdk
     EMSCRIPTEN_PATH    ?= $(EMSDK_PATH)/upstream/emscripten
     CLANG_PATH          = $(EMSDK_PATH)/upstream/bin
-    PYTHON_PATH         = $(EMSDK_PATH)/python/2.7.13.1_64bit/python-2.7.13.amd64
+    PYTHON_PATH         = $(EMSDK_PATH)/python/3.7.4_64bit
     NODE_PATH           = $(EMSDK_PATH)/node/12.9.1_64bit/bin
     export PATH         = $(EMSDK_PATH);$(EMSCRIPTEN_PATH);$(CLANG_PATH);$(NODE_PATH);$(PYTHON_PATH);C:\raylib\MinGW\bin:$$(PATH)
 endif
@@ -478,7 +478,7 @@ endif
 raylib: $(OBJS)
 ifeq ($(PLATFORM),PLATFORM_WEB)
     # Compile raylib for web.
-	emcc -O1 $(OBJS) -o $(RAYLIB_RELEASE_PATH)/libraylib.bc
+	$(CC) -O1 $(OBJS) -o $(RAYLIB_RELEASE_PATH)/libraylib.bc
 	@echo "raylib library generated (libraylib.bc)!"
 else
     ifeq ($(RAYLIB_LIBTYPE),SHARED)

src/core.c

@@ -703,7 +703,7 @@ void InitWindow(int width, int height, const char *title)
 #endif
 
 #if defined(PLATFORM_WEB)
-    emscripten_set_fullscreenchange_callback(0, 0, 1, EmscriptenFullscreenChangeCallback);
+    emscripten_set_fullscreenchange_callback("#canvas", NULL, 1, EmscriptenFullscreenChangeCallback);
 
     // Support keyboard events
     emscripten_set_keypress_callback("#canvas", NULL, 1, EmscriptenKeyboardCallback);