MinGW: Fix native TLS bug with -fdata-sections

MinGW: Fix native TLS bug with -fdata-sections

The problem comes from a quirk of the GNU PE-COFF linker, which wants
to make sure that .tls$ZZZ is laid out last among the TLS sections,
but first globs all .tls$* sections together.  The solution matches
Clang's output.

gcc/
	PR target/80881
	* config/mingw/winnt.cc (mingw_pe_unique_section): Put two dollar
	signs for TLS sections after the prefix.
	(mingw_pe_asm_named_section): Deal with all TLS sections uniformly.

gcc/testsuite/
	* gcc.dg/tls/data-sections-1.c: New test.