moving a bracket in a commented out code block incorrectly colors other brackets

[asifamin13]

Steps to reproduce:

1. Comment out code block
2. mouse over to a space before an open bracket in the commented section
3. insert space

[asifamin13]

Encountered here

[asifamin13]

SCI_BRACEMATCH can give incorrect answers depending on how fast its called when styling changes.

I was able to fix this by checking if I try to brace match a non source section and delaying the computation until later

[asifamin13]

did a clean build of geany and geany-plugins and verified this fixes the issue

arlut@trix:~/geany-plugins$ geany -V
geany 2.1 (git >= 30f84de9a) (built on 2024-10-04 with GTK 3.24.38, GLib 2.78.0)