Change profile-build options to produce 1% to 2% faster executables.

The "@rm ucioption.gc*" line is necessary to avoid a gcc 4.7.x bug.
Confirmed for gcc 4.7.4, 4.8.1, and 4.9.1
Suggested by Kiran Panditrao on fishcooking forum.
https://groups.google.com/forum/?fromgroups=#!topic/fishcooking/AY8gN53nG18

No functional change.

Resolves #160

src/Makefile

@@ -373,6 +373,9 @@ profile-build:
 	@$(PGOBENCH) > /dev/null
 	@echo ""
 	@echo "Step 3/4. Building final executable ..."
+# Deleting corrupt ucioption.gc* profile files is necessary to avoid an 
+# "internal compiler error" for gcc versions 4.7.x
+	@rm ucioption.gc*
 	@touch *.cpp *.h syzygy/*.cpp syzygy/*.h
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) $(profile_use)
 	@echo ""
@@ -439,13 +442,13 @@ gcc-profile-prepare:
 
 gcc-profile-make:
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
-	EXTRACXXFLAGS='-fprofile-generate' \
+	EXTRACXXFLAGS='-fprofile-arcs' \
 	EXTRALDFLAGS='-lgcov' \
 	all
 
 gcc-profile-use:
 	$(MAKE) ARCH=$(ARCH) COMP=$(COMP) \
-	EXTRACXXFLAGS='-fprofile-use' \
+	EXTRACXXFLAGS='-fbranch-probabilities' \
 	EXTRALDFLAGS='-lgcov' \
 	all