Enable LTO unless NO_LTO is defined...

We may want to set NO_LTO for the pipeline...

src/build/Common.gmake

@@ -51,6 +51,7 @@
 #  OBJPATH_SUFFIX	- Suffix appended to OBJPATH useful for compiling 		#
 #					  different options of the same source file				#
 #  STATIC			- Create a statically linked build if possible			#
+#  NO_LTO            - Disable Link-Time Optimizations                      #
 #																			#
 # Common Build Macros Defined:												#
 #  DELETE			- Delete files (Preferrably verbose)					#
@@ -496,6 +497,10 @@ else # RELEASE
  # -finline-functions (used to) break the baja build badly.
  # This also meant that -O3 wouldn't work either.
  CFLAGS	:= -O3 -Wno-unused-result -fomit-frame-pointer -ffast-math -funroll-loops $(CFLAGS)
+ ifndef NO_LTO
+  CFLAGS += -flto
+  LDFLAGS += -flto
+ endif
 endif
 CFLAGS += -fno-delete-null-pointer-checks