contrib: support CMAKE_GENERATOR other than makefile

First, fix the conflict setting/using of CMAKE_GENERATOR. Second,
call build via cmake instead of run make directly.

Signed-off-by: Alexandre Janniaux <ajanni@videolabs.io>
(cherry picked from commit c74a77e7) (edited)
edited:
- only use the patch for glew that is now built with CMake

contrib/src/glew/rules.mak

@@ -18,5 +18,5 @@ glew: glew-$(GLEW_VERSION).tgz .sum-glew
 
 .glew: glew toolchain.cmake
 	cd $</build/cmake && $(HOSTVARS_PIC) $(CMAKE) -DBUILD_SHARED_LIBS:BOOL=OFF -DGLEW_USE_STATIC_LIBS:BOOL=ON
-	cd $</build/cmake && $(MAKE) install
+	cd $</build/cmake && $(CMAKEBUILD) . --target install
 	touch $@