* vm_exec.h (END_INSN): llvm-gcc may optimize out reg_cfp and cause
  Stack/cfp consistency error when the instruction doesn't use reg_cfp.
  Usually instructions use PUSH() but for example trace doesn't.
  This hack cause speed down but you shouldn't use llvm-gcc, use clang.
  [Bug #7938]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39517 b2dd03c8-39d4-4d8f-98ff-823fe69b080e