games-fps/assaultcube: fix compile failure with clang

Closes: https://bugs.gentoo.org/921915
Signed-off-by: Takuya Wakazono <pastalian46@gmail.com>

games-fps/assaultcube/files/assaultcube-1.3.0.2-unset-variables.patch

@@ -0,0 +1,32 @@
+Respect user preferences during the build and fix the Clang build by
+disabling PCH.
+https://bugs.gentoo.org/921915
+--- a/source/src/Makefile
++++ b/source/src/Makefile
+@@ -6,7 +6,6 @@
+ # found to have been caused by the g++ compiler in the past. This seems to have
+ # been fixed now by relaxing the optimization that g++ does, so although we'll
+ # continue using clang++ (just in case), you can use g++ if you prefer.
+-CXX=clang++
+ 
+ # call like 'DEBUGBUILD=1 make' to compile a debug version of AssaultCube.
+ ifdef DEBUGBUILD
+@@ -34,10 +33,8 @@ ifeq ($(ACDEBUG),yes)
+ endif
+ 
+ ifneq (,$(findstring clang,$(CXX)))
+-	CXXFLAGS= -O3 -fomit-frame-pointer
+ 	override CXXFLAGS+= -Wall -fsigned-char
+ else
+-	CXXFLAGS= -O3 -fomit-frame-pointer
+ 	override CXXFLAGS+= -Wall -fsigned-char -ffast-math -rdynamic -Wno-format-zero-length
+ 	ifeq "$(shell expr 'gcc -dumpversion' \>= 8)" "1"
+ 		override CXXFLAGS+= -Wno-stringop-truncation
+@@ -182,7 +179,6 @@ rendermodel.o: rendermodel.cpp
+ 	$(CXX) $(CXXFLAGS) -c -o $@ $(subst -standalone.o,.cpp,$@)
+ 
+ $(CLIENT_OBJS): CXXFLAGS += $(CLIENT_INCLUDES)
+-$(CLIENT_OBJS): $(CLIENT_PCH)
+ $(SERVER_OBJS): CXXFLAGS += $(SERVER_INCLUDES)
+ $(filter-out $(SERVER_OBJS),$(MASTER_OBJS)): CXXFLAGS += $(SERVER_INCLUDES)
+