Only check ARCH_ARM_HAVE_ARMV7A if TARGET_ARCH is arm

This patch is required to enable chrome http stack on x86.

This is just clean-up to make it the same as the WebKit change:
https://android-review.googlesource.com/#/c/30891

Change-Id: Ie88ab86de9a32de5e8b02adb129e01203dd5637a

Author: cwhuang

media/libstagefright/Android.mk

@@ -95,11 +95,11 @@ LOCAL_STATIC_LIBRARIES := \
 # currently must follow the same logic to determine how webkit was built and
 # if it's safe to link against libchromium.net
 
-# V8 also requires an ARMv7 & x86 CPU, and since we must use jsc, we cannot
+# On ARM, V8 also requires an ARMv7 CPU, and since we must use jsc, we cannot
 # use the Chrome http stack either.
-ifneq ($(strip $(ARCH_ARM_HAVE_ARMV7A)),true)
-  ifneq ($(TARGET_ARCH),x86)
-      USE_ALT_HTTP := true
+ifeq ($(TARGET_ARCH),arm)
+  ifneq ($(strip $(ARCH_ARM_HAVE_ARMV7A)),true)
+    USE_ALT_HTTP := true
   endif
 endif