Add DWARF5 variants of assembly scan tests that use DW_FORM_implicit_const

Add DWARF5 variants of assembly scan tests that use DW_FORM_implicit_const

Some DWARF tests scan the assembly output looking for constant values.
When using DWARF5 those constants might use DW_FORM_implicit_const,
which are output (in the comments) after the attribute instead of
before. To make sure these tests work introduce a -gdwarf-5 variant
of these tests and explicitly use -gdwarf-2 for the original.

gcc/testsuite/ChangeLog:

	* gcc.dg/debug/dwarf2/inline2.c: Add -gdwarf-2.
	* g++.dg/debug/dwarf2/inline-var-1.C: Likewise.
	* gcc.dg/debug/dwarf2/pr41445-5.c: Likewise.
	* gcc.dg/debug/dwarf2/pr41445-6.c: Likewise.
	* gcc.dg/debug/dwarf2/inline6.c: New variant with -gdwarf-5.
	* g++.dg/debug/dwarf2/inline-var-3.C: Likewise.
	* gcc.dg/debug/dwarf2/pr41445-7.c: Likewise.
	* gcc.dg/debug/dwarf2/pr41445-8.c: Likewise.