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

Author: the-eater

.github/labeler.yml

@@ -6,9 +6,13 @@
 
 "Category: Build System":
 - build/*
+- win32/build/*
 - scripts/**/*
 - '**/*.m4'
 - '**/*.w32'
+- buildconf.bat
+- buildconf
+- configure.ac
 
 "Extension: bcmath":
 - ext/bcmath/**/*