[gdb/testsuite] Add test-case gdb.dwarf2/break-inline-psymtab.exp

[gdb/testsuite] Add test-case gdb.dwarf2/break-inline-psymtab.exp

Add a test-case that tests whether we can set a breakpoint on an inlined
inline function in CU for which the partial symtab has not yet been expanded.

Tested on x86_64-linux, with gcc 4.8.5, gcc-7.5.0, gcc-10.0.1, and clang
5.0.2.

gdb/testsuite/ChangeLog:

2020-03-18  Tom de Vries  <tdevries@suse.de>

	* gdb.dwarf2/break-inline-psymtab-2.c: New test.
	* gdb.dwarf2/break-inline-psymtab.c: New test.
	* gdb.dwarf2/break-inline-psymtab.exp: New file.