fix(build): do not use != assignment in Makefiles (#5464)

GNU Make 3.81 that ships with MacOSX does not understand '!= ...' assignment
so we use ':= $(shell ...)' instead which have the same behavior here.

Additionally, I have changed the use of 'type' to 'command -v'
because assigning the result of 'type' to variable named 'EMMAKE'
does not make much sense. I also reused this variable.

For more detailed information read the linked issue.

Fixes: https://github.com/raysan5/raylib/issues/5460

examples/Makefile

@@ -213,9 +213,9 @@ ifeq ($(TARGET_PLATFORM),$(filter $(TARGET_PLATFORM),PLATFORM_WEB PLATFORM_WEB_R
     ifeq ($(PLATFORM_OS),WINDOWS)
         MAKE = mingw32-make
     else
-        EMMAKE != type emmake
+        EMMAKE := $(shell command -v emmake)
         ifneq (, $(EMMAKE))
-            MAKE = emmake make
+            MAKE = $(EMMAKE) make
         else
             MAKE = mingw32-make
         endif

examples/Makefile.Web

@@ -211,9 +211,9 @@ ifeq ($(TARGET_PLATFORM),$(filter $(TARGET_PLATFORM),PLATFORM_WEB PLATFORM_WEB_R
     ifeq ($(PLATFORM_OS),WINDOWS)
         MAKE = mingw32-make
     else
-        EMMAKE != type emmake
+        EMMAKE := $(shell command -v emmake)
         ifneq (, $(EMMAKE))
-            MAKE = emmake make
+            MAKE = $(EMMAKE) make
         else
             MAKE = mingw32-make
         endif