Make it actually work to build GLEW for debugging

The check in the GLEW Makefile looked at the whole $(MAKECMDGOALS),
which in our case was the string 'glew.lib debug', not just 'debug'.

Change-Id: I639395c944e8f2b443cbb55b451a4036b2c9d3bb

external/glew/UnpackedTarball_glew.mk

@@ -48,4 +48,8 @@ $(eval $(call gb_UnpackedTarball_add_patches,glew,\
 ))
 endif
 
+$(eval $(call gb_UnpackedTarball_add_patches,glew,\
+	external/glew/glew-debug.patch.1 \
+))
+
 # vim: set noet sw=4 ts=4:

external/glew/glew-debug.patch.1

+-*- Mode: Diff -*-
+--- glew/Makefile
++++ glew/Makefile
+@@ -65,7 +65,7 @@
+ RM      ?= rm -f
+ LN      ?= ln -sf
+ 
+-ifeq ($(MAKECMDGOALS), debug)
++ifneq (,$(filter debug,$(MAKECMDGOALS)))
+ OPT = -g
+ else
+ OPT = $(POPT)