Add WALL option.

src/build/Common.gmake

@@ -94,7 +94,8 @@
 #  MT_LDFLAGS		- LDFLAGS for linking MT targets						#
 #  UL_PRE			- Use Library prefix (*nix is -l)						#
 #  UL_SUF			- Use Library siffix (bcc is .lib)						#
-#  WERROR           - Error on warnings                                     #
+#  WERROR           - Error on warnings (-Werror)                           #
+#  WALL             - All warnings, even for a RELEASE build (-Wall)        #
 #																			#
 # Common Targets Defined:													#
 #  Implicit C and C++ targets												#
@@ -164,10 +165,12 @@ ifndef VERBOSE
  QUIET	:=	@
 endif
 
-# WERROR
 ifdef WERROR
  CFLAGS += -Werror
 endif
+ifdef WALL
+ CFLAGS += -Wall
+endif
 
 # Compiler-specific options
 CFLAGS	+=	-MMD