Update stagefright makefile after dropping support for JSC

# The following was shamelessly copied from external/webkit/Android.mk and

# 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 CPU, and since we must use jsc, we cannot

# use the Chrome http stack either.

ifneq ($(strip $(ARCH_ARM_HAVE_ARMV7A)),true)

  USE_ALT_HTTP := true

endif

# if it's safe to link against libchromium_net

# See if the user has specified a stack they want to use

HTTP_STACK = $(HTTP)