Add a make target for profiling

Makefile

@@ -1,4 +1,5 @@
-GCCFLAGS=-g -Iinclude -Wall -MMD -fno-omit-frame-pointer -O
+PROFILE_FLAGS=
+GCCFLAGS=-g -Iinclude -Wall -MMD -fno-omit-frame-pointer -O $(PROFILE_FLAGS)
 CXXFLAGS=$(GCCFLAGS) -W -Werror
 CFLAGS=$(GCCFLAGS) -fPIC
 
@@ -29,6 +30,9 @@ endif
 
 all: $(EXES)
 
+profile:
+	make clean all PROFILE_FLAGS=-pg
+
 mach: $(MAC_TARGETS)
 
 check: all mach
@@ -48,13 +52,13 @@ $(MACTXTS): %.txt: %.bin
 #	touch $@
 
 extract: extract.o fat.o
-	$(CXX) $^ -o $@ -g -I. -W -Wall
+	$(CXX) $^ -o $@ -g -I. -W -Wall $(PROFILE_FLAGS)
 
 macho2elf: macho2elf.o mach-o.o fat.o log.o
-	$(CXX) $^ -o $@ -g
+	$(CXX) $^ -o $@ -g $(PROFILE_FLAGS)
 
 ld-mac: ld-mac.o mach-o.o fat.o log.o
-	$(CXX) $^ -o $@ -g -ldl -lpthread
+	$(CXX) $^ -o $@ -g -ldl -lpthread $(PROFILE_FLAGS)
 
 # TODO(hamaji): autotoolize?
 libmac/libmac.so: libmac/mac.o