allow $ in scan-tree-dump expressions matching symbol names

This change adjusts a few scan-tree-dump expressions
to allow '$' as well as '.' when matching symbol names,

This improves results on VxWorks targets configured with:

 #undef NO_DOLLAR_IN_LABEL
 #define NO_DOT_IN_LABEL

2019-12-20  Olivier Hainque  <hainque@adacore.com>
           Jerome Lambourg  <lambourg@adacore.com>

	* c-c++-common/pr56493.c: Allow '$' in addition to '.'
	scan-tree-dump expressions matching symbol names.
	* gcc.dg/tree-ssa/sra-17.c: Likewise.
	* gcc.dg/tree-ssa/sra-18.c: Likewise.

Co-Authored-By: Jerome Lambourg <lambourg@adacore.com>

From-SVN: r279794