github: add buildconf, configure.ac and win32 build folder to build system category

Author: the-eater

.github/labeler.yml

@@ -5,8 +5,12 @@
 - Zend/Optimizer/**/*
 
 "Category: Build System":
-- build/*
+- buildconf.bat
+- buildconf
+- build/**/*
+- configure.ac
 - scripts/**/*
+- win32/build/**/*
 - '**/*.m4'
 - '**/*.w32'