Author: Nils Freydank <holgersson@posteo.de>
Date:   Fri Nov 17 20:30:00 2017 +0100

Respect CFLAGS, CPPFLAGS etc. This patch is inspired
by hasufell’s patch.

Edit 2018-03-19: Now with server support!
Edit 2018-09-01: Update to take Makefile changes into account.

--- a/Makefile	2018-07-08 11:00:00.000000000 +0200
+++ b/Makefile	2018-09-01 11:00:00.000000001 +0200
@@ -308,34 +308,33 @@
 CLIENT_EXTRA_FILES=
 
 ifneq (,$(findstring "$(PLATFORM)", "linux" "gnu_kfreebsd" "kfreebsd-gnu" "gnu"))
-  BASE_CFLAGS = -Wall -fno-strict-aliasing -Wimplicit -Wstrict-prototypes \
-    -pipe -DUSE_ICON -DARCH_STRING=\\\"$(ARCH)\\\"
+  BASE_CFLAGS = -DUSE_ICON -DARCH_STRING=\\\"$(ARCH)\\\"
   CLIENT_CFLAGS += $(SDL_CFLAGS)
 
-  OPTIMIZEVM = -O3
-  OPTIMIZE = $(OPTIMIZEVM) -ffast-math
+  OPTIMIZEVM =
+  OPTIMIZE = $(OPTIMIZEVM)
 
   ifeq ($(ARCH),x86_64)
-    OPTIMIZEVM = -O3
-    OPTIMIZE = $(OPTIMIZEVM) -ffast-math
+    OPTIMIZEVM =
+    OPTIMIZE = $(OPTIMIZEVM)
     HAVE_VM_COMPILED = true
   else
   ifeq ($(ARCH),x86)
-    OPTIMIZEVM = -O3 -march=i586
-    OPTIMIZE = $(OPTIMIZEVM) -ffast-math
+    OPTIMIZEVM =
+    OPTIMIZE = $(OPTIMIZEVM)
     HAVE_VM_COMPILED=true
   else
   ifeq ($(ARCH),ppc)
-    ALTIVEC_CFLAGS = -maltivec
+    ALTIVEC_CFLAGS =
     HAVE_VM_COMPILED=true
   endif
   ifeq ($(ARCH),ppc64)
-    ALTIVEC_CFLAGS = -maltivec
+    ALTIVEC_CFLAGS =
     HAVE_VM_COMPILED=true
   endif
   ifeq ($(ARCH),sparc)
-    OPTIMIZE += -mtune=ultrasparc3 -mv8plus
-    OPTIMIZEVM += -mtune=ultrasparc3 -mv8plus
+    OPTIMIZE +=
+    OPTIMIZEVM +=
     HAVE_VM_COMPILED=true
   endif
   ifeq ($(ARCH),armv7l)
@@ -1143,7 +1142,7 @@
 
 define DO_CC
 $(echo_cmd) "CC $<"
-$(Q)$(CC) $(NOTSHLIBCFLAGS) $(CFLAGS) $(CLIENT_CFLAGS) $(OPTIMIZE) -o $@ -c $<
+$(Q)$(CC) $(NOTSHLIBCFLAGS) $(CFLAGS) $(CPPFLAGS) $(CLIENT_CFLAGS) $(OPTIMIZE) -o $@ -c $<
 endef
 
 define DO_CC_ALTIVEC
@@ -1153,7 +1152,7 @@
 
 define DO_REF_CC
 $(echo_cmd) "REF_CC $<"
-$(Q)$(CC) $(SHLIBCFLAGS) $(CFLAGS) $(CLIENT_CFLAGS) $(OPTIMIZE) -o $@ -c $<
+$(Q)$(CC) $(SHLIBCFLAGS) $(CFLAGS) $(CPPFLAGS) $(CLIENT_CFLAGS) $(OPTIMIZE) -o $@ -c $<
 endef
 
 define DO_REF_CC_ALTIVEC
@@ -1171,7 +1170,7 @@
 
 define DO_BOT_CC
 $(echo_cmd) "BOT_CC $<"
-$(Q)$(CC) $(NOTSHLIBCFLAGS) $(CFLAGS) $(BOTCFLAGS) $(OPTIMIZE) -DBOTLIB -o $@ -c $<
+$(Q)$(CC) $(NOTSHLIBCFLAGS) $(CFLAGS) $(CPPFLAGS) $(BOTCFLAGS) $(OPTIMIZE) -DBOTLIB -o $@ -c $<
 endef
 
 ifeq ($(GENERATE_DEPENDENCIES),1)
@@ -1185,7 +1184,7 @@
 
 define DO_DED_CC
 $(echo_cmd) "DED_CC $<"
-$(Q)$(CC) $(NOTSHLIBCFLAGS) -DDEDICATED $(CFLAGS) $(SERVER_CFLAGS) $(OPTIMIZE) -o $@ -c $<
+$(Q)$(CC) $(NOTSHLIBCFLAGS) -DDEDICATED $(CFLAGS) $(CPPFLAGS) $(SERVER_CFLAGS) $(OPTIMIZE) -o $@ -c $<
 endef
 
 define DO_WINDRES