kbuild,gcov: simplify kernel/gcov/Makefile more

CONFIG_GCOV_FORMAT_3_4 / _4_7 / _AUTODETECT are exclusive.
Compare the CC version only when _AUTODETECT is enabled.

This change should have no impact.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

kernel/gcov/Makefile

 ccflags-y := -DSRCTREE='"$(srctree)"' -DOBJTREE='"$(objtree)"'
 
-# if-lt
-# Usage VAR := $(call if-lt, $(a), $(b))
-# Returns 1 if (a < b)
-if-lt = $(shell [ $(1) -lt $(2) ] && echo 1)
-
-ifeq ($(CONFIG_GCOV_FORMAT_3_4),y)
-  cc-ver := 0304
-else ifeq ($(CONFIG_GCOV_FORMAT_4_7),y)
-  cc-ver := 0407
-else
-  cc-ver := $(cc-version)
-endif
-
 obj-y := base.o fs.o
-
-ifeq ($(call if-lt, $(cc-ver), 0407),1)
-  obj-y += gcc_3_4.o
-else
-  obj-y += gcc_4_7.o
-endif
+obj-$(CONFIG_GCOV_FORMAT_3_4) += gcc_3_4.o
+obj-$(CONFIG_GCOV_FORMAT_4_7) += gcc_4_7.o
+obj-$(CONFIG_GCOV_FORMAT_AUTODETECT) += $(call cc-ifversion, -lt, 0407, \
+							gcc_3_4.o, gcc_4_7.o)