Revert "V8: enable no-pic compiling option"

This is inducing a huge number of text relocations on Android
x86, preventing certain security hardening and wasting memory.

This reverts commit 5516927b9231f622e1db0606ea876df4cefb9ce6.

Bug: 11353056
Change-Id: I297b1ef1844818b182780f2cbec7c75dd030f9f8
Hide warning about unused parameters for v8

Change-Id: Idf51193d14812cac0b97f2ad9cbefc79efb8da42
v8: support multilib builds

Allow building for multiple architectures at the same time:
Use $(local-generated-sources-dir) instead of $(local-intermediates-dir)
Set LOCAL_CFLAGS_arch instead of ifeq ($(TARGET_ARCH),arch)
Use LOCAL_MODULE_TARGET_ARCH_WARN to restrict which architectures
attempt to build, and print a warning on the rest.

Change-Id: I66dffb36557aa47c92a1ae158683a27e9ca83e53