mips.c (mips16_build_call_stub): Zero-extend the low half of a single-register SCmode...

mips.c (mips16_build_call_stub): Zero-extend the low half of a single-register SCmode return value before ORing...

gcc/
	* config/mips/mips.c (mips16_build_call_stub): Zero-extend the
	low half of a single-register SCmode return value before ORing
	it with the high half.
	* config/mips/mips16.S (MERGE_GPRf): Likewise.

gcc/testsuite/
	* gcc.target/mips/mips16-attributes-4.c: New test.

From-SVN: r162283