x86-64: Remove pr19609-4c.d and pr19609-4d.d

Remove pr19609-4c.d and pr19609-4d.d since they are identical to
pr19609-4a.d and pr19609-4b.d, respectively.

	* testsuite/ld-x86-64/pr19609-4c.d: Removed.
	* testsuite/ld-x86-64/pr19609-4d.d: Likewise.
	* testsuite/ld-x86-64/pr19609-4e.d: Renamed to ...
	* testsuite/ld-x86-64/pr19609-4c.d: This.
	* testsuite/ld-x86-64/x86-64.exp: Updated.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>