Fix frame-apply.html collision in GDB manual.

Fix frame-apply.html collision in GDB manual.

The addition of an anchor for the "frame apply" command was causing
the HTML documentation to include files named both "frame-apply.html"
and "Frame-Apply.html", which collide on case-insensitive file
systems.  This patch removes the redundant anchor and adjusts the two
xrefs to it.

2020-07-13 Paul Carroll <pcarroll@codesourcery.com>

	PR gdb/25716

	gdb/doc/
	* gdb.texinfo (Frame Apply): Remove anchor for 'frame
	apply' and adjust xrefs to it.