gfortran: Respect target's NO_DOT_IN_LABEL in trans-common.cc

gfortran: Respect target's NO_DOT_IN_LABEL in trans-common.cc

This patch fixes 9 unexpected failures in the gfortran testsuite on
nvptx-none.  The issue is that gfortran's EQUIVALENCE internally uses
symbols such as "equiv.0" even on platforms that define NO_DOT_IN_LABEL.
On nvptx-none, this then results in the following error message(s):
ptxas application ptx input, fatal: Parsing error near '.0': syntax error
ptxas fatal: Ptx assembly aborted due to errors

The fix is to tweak trans-common.cc to respect the target's NO_DOT_IN_LABEL
(and NO_DOLLAR_IN_LABEL) when generating internal equiv.%d symbols.
Only the nvptx, mmix and xtensa backends define NO_DOT_IN_LABEL which
explains why no-one has spotted/fixed this issue since the problematic
code was last changed back in 2005(!).

2022-02-10  Roger Sayle  <roger@nextmovesoftware.com>
	    Tobias Burnus  <tobias@codesourcery.com>

gcc/fortran/ChangeLog
	* trans-common.cc (GFC_EQUIV_FMT): New macro respecting the
	target's NO_DOT_IN_LABEL and NO_DOLLAR_IN_LABEL preferences.
	(build_equiv_decl): Use GFC_EQUIV_FMT here.