Fix ICE with -fopt-info-inline (PR ipa/87955)

Fix ICE with -fopt-info-inline (PR ipa/87955)

PR ipa/87955 reports a problem I introduced in r265920, where I converted
the guard in report_inline_failed_reason from using:
  if (dump_file)
to using
  if (dump_enabled_p ()).
without updating the calls to cl_target_option_print_diff and
cl_optimization_print_diff, which assume that dump_file is non-NULL.

The functions are auto-generated.  Rather than porting them to the dump
API, this patch applies the workaround of adding the missing checks on
dump_file before calling them.

gcc/ChangeLog:
	PR ipa/87955
	* ipa-inline.c (report_inline_failed_reason): Guard calls to
	cl_target_option_print_diff and cl_optimization_print_diff with
	if (dump_file).

gcc/testsuite/ChangeLog:
	PR ipa/87955
	* gcc.target/i386/pr87955.c: New test.

From-SVN: r266079