Promote do_lookup_x:check_match to a full function.

Promote do_lookup_x:check_match to a full function.

While it may be argued that nested functions make the resulting
code easier to read, or worse to read the following two bugs
make it difficult to debug:

Bug 8300 - no local symbol information within nested or nesting
procedures
https://sourceware.org/bugzilla/show_bug.cgi?id=8300

Bug 53927 - wrong value for DW_AT_static_link
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53927

Until these are fixed I've made check_match a full function.
After they are fixed we can resume arguing about the merits
of nested functions on readability and maintenance.