[Darwin, X86, testsuite] Update tests for common section use.

[Darwin, X86, testsuite] Update tests for common section use.

The tests amended here now have different code-gen with default
options because, previously, the access were indirected per Darwin
ABI for common accesses.  The revised code-gen does not match the
expected scan-asms because Darwin defaults to fPIC.  For these tests,
it seems that the best solution is to use '-mdynamic-no-pic' in the
m32 case which makes the output similar to the ElF platform default.

gcc/testsuite/ChangeLog:

2019-11-22  Iain Sandoe  <iain@sandoe.co.uk>

	* gcc.target/i386/pr27971.c: Use mdynamic-no-pic for m32 on
	Darwin.
	* gcc.target/i386/sse2-load-multi.c: Likewise.
	* gcc.target/i386/sse2-store-multi.c: Likewise.

From-SVN: r278631