zero-scratch-regs-[29|30].c: Disable TARGET_USE_FFREEP

Compile zero-scratch-regs-[29|30].c with -mtune-ctrl=^use_ffreep to
disable using freep instruction instead of fstp to avoid:

FAIL: gcc.target/i386/zero-scratch-regs-29.c scan-assembler-times fstp[ \t]+%st\
\(0\\) 7
FAIL: gcc.target/i386/zero-scratch-regs-29.c scan-assembler-times fstp[ \t]+%st\
\(0\\) 7
FAIL: gcc.target/i386/zero-scratch-regs-30.c scan-assembler-times fstp[ \t]+%st\
\(0\\) 6
FAIL: gcc.target/i386/zero-scratch-regs-30.c scan-assembler-times fstp[ \t]+%st\
\(0\\) 8

when TARGET_USE_FFREEP is enabled by default.

	PR testsuite/126923
	* gcc.target/i386/zero-scratch-regs-29.c (dg-options): Add
	-mtune-ctrl=^use_ffreep.
	* gcc.target/i386/zero-scratch-regs-30.c (dg-options): Likewise.

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