[PATCH] dwarf2read.c (dw2_expand_symtabs_matching): Add some QUIT calls.

[Doug Evans]

Doug Evans writes:
 > Hi.
 > 
 > "info fun foo" can be a pain when it's not interruptable,
 > especially if you're not exactly sure of what you're looking for
 > and provide something that matches too much.
 > 
 > 2015-03-30  Doug Evans  <dje@google.com>
 > 
 > 	* dwarf2read.c (dw2_expand_symtabs_matching): Add some QUIT calls.

Committed.