Eases the use of clang in the makefile

New definition in the makefile for warnings that are valid for gcc but
not for clang (CWARNGCC).

makefile

@@ -5,7 +5,7 @@
 
 # Warnings valid for both C and C++
 CWARNSCPP= \
-	-fmax-errors=5 \
+	-Wfatal-errors \
 	-Wextra \
 	-Wshadow \
 	-Wsign-compare \
@@ -14,8 +14,6 @@ CWARNSCPP= \
 	-Wredundant-decls \
 	-Wdisabled-optimization \
 	-Wdouble-promotion \
-	-Wlogical-op \
-	-Wno-aggressive-loop-optimizations \
         # the next warnings might be useful sometimes,
 	# but usually they generate too much noise
 	# -Werror \
@@ -26,6 +24,13 @@ CWARNSCPP= \
 	# -Wformat=2 \
 	# -Wcast-qual \
 
+
+# Warnings for gcc, not valid for clang
+CWARNGCC= \
+	-Wlogical-op \
+	-Wno-aggressive-loop-optimizations \
+
+
 # The next warnings are neither valid nor needed for C++
 CWARNSC= -Wdeclaration-after-statement \
 	-Wmissing-prototypes \
@@ -35,7 +40,7 @@ CWARNSC= -Wdeclaration-after-statement \
 	-Wold-style-definition \
 
 
-CWARNS= $(CWARNSCPP) $(CWARNSC)
+CWARNS= $(CWARNSCPP) $(CWARNSC) $(CWARNGCC)
 
 # Some useful compiler options for internal tests:
 # -DLUAI_ASSERT turns on all assertions inside Lua.