v.label.sa: Fix Resource Leak issue in labels.c

[ShubhamDesai]

This pull request fixes issue identified by Coverity Scan(CID : 1415681, 1415703, 1415745, 1415754)
Used Vect_destroy_field_info(), G_free(), Vect_destroy_list() to fix this issue

[nilason]

Looks good so far. There remains a single issue for the v.label.sa module in the file font.c, please address that one here too.

[ShubhamDesai]

Looks good so far. There remains a single issue for the v.label.sa module in the file font.c, please address that one here too.

done.
Updated the loop so that as soon as we hit the first matching entry we call G_malloc() once, populate the struct fields using font_cap->… instead of font_cap[fonts_count] (because font_cap points to a single GFONT_CAP, not an array, and -> safely dereferences that one object), and immediately break; out of the loop—this guarantees exactly one allocation per call, removes any chance of overwriting (and leaking) a previous pointer, fixes the undefined‐behavior of array‐style indexing on a lone allocation.