Revert "Optimizing String.Equals as an intrinsic (x86)"

Reverted as it breaks the compilation of boot.{oat,art} on x86 (although this CL may not be the culprit, as the issue seems to come from Optimizing's register allocator).

This reverts commit 8ab7bd6c8b10ad58758c33a1dc9326212bd200e9.

Change-Id: If7c8b6258d1e690f4d2a06bcc82c92563ac6cdef
9 files changed