Darwin, x86, testsuite - adjust tests for Darwin PR90698.

Darwin, x86, testsuite - adjust tests for Darwin PR90698.

We don't have support for -mcmodel={medium, large, kernel} so don't
expect tests for those things to work.

For now mark them as xfail where possible and skip where that isn't.
These changes will be logged onto the PR and therefore can be backed
out when the facility is implemented.

gcc/testsuite/ChangeLog:

2019-06-01  Iain Sandoe  <iain@sandoe.co.uk>

	PR target/90698
	* gcc.target/i386/pr49866.c: XFAIL for Darwin.
	* gcc.target/i386/pr63538.c: Likewise.
	* gcc.target/i386/pr61599-1.c: Skip for Darwin.

From-SVN: r271839