ART: String DexCache asm fast path for ARM64

In the entrypoints, before a string is looked up in the slow path (in
the intern table), I added assembly to check the dex cache and return a
string pointer if the string is already in the dex cache.

Test: test-art-host

Change-Id: Ic9a724848c61e4fa66e82334e2c7b20b13bf8e6c
1 file changed