[X86] Use BuildStackAdjustment in stack probes

This has the advantage of dealing with live EFLAGS, using LEA instead of
SUB if needed to avoid clobbering. That also respects feature "lea-sp".

We could allow unrolled stack probing from blocks with live-EFLAGS, if
canUseAsEpilogue learns when emitStackProbeInlineGeneric will be used.

Differential Revision: https://reviews.llvm.org/D134495