[gdb/testsuite] Force DWARF in gdb.pascal

On i686-linux (and likewise arm-linux), I run into:
...
(gdb) file str-chars^M
Reading symbols from str-chars...^M
warning: stabs debug information is not supported.^M
(No debugging symbols found in str-chars)^M
(gdb) delete breakpoints^M
...

Fix this by using fpc option -gw2.

Tested on i686-linux.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

PR testsuite/33564
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33564

gdb/testsuite/lib/pascal.exp

@@ -128,7 +128,9 @@ proc fpc_compile {source destfile type options} {
 	    if {[board_info $dest exists debug_flags]} {
 		append add_flags " [board_info $dest debug_flags]"
 	    } else {
-		append add_flags " -g"
+		# GDB no longer supports STABS, so force DWARF debug info.
+		# Use v2 assuming support is more mature than later versions.
+		append add_flags " -g -gw2"
 	    }
 	}
 	if { $i == "class" } {