[AMDGPU] Don't constrain callees with inlinehint from inlining on MaxBB check

Summary: Function bodies marked inline in an opencl source are eliminated but MaxBB check may prevent inlining them leaving undefined references.

Reviewers: rampitec, arsenm

Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, Anastasia, t-tye, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63337

llvm-svn: 363418