sse-init-v2df-1.c: Compile with -mfpmath=sse

When GCC is configured with --with-fpmath=sse, i386/ssemath.h is used,
which has

 #undef TARGET_FPMATH_DEFAULT_P
 #define TARGET_FPMATH_DEFAULT_P(x) \
  (TARGET_SSE2_P(x) ? FPMATH_SSE : FPMATH_387)

SSE math is disabled with -mno-sse2.  Since sse-init-v2df-1.c requires
SSE math, compile sse-init-v2df-1.c with -mfpmath=sse so that SSE math
is enabled with "-mno-sse2"

	* gcc.target/i386/sse-init-v2df-1.c: Compile with -mfpmath=sse.

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