pmb.helpers.pmaports: parse guessed APKBUILD first for speed up (MR 2132)

At the moment we have to parse all APKBUILDs to find subpackages,
even if they are guessed easily shortly after. To speed this up,
let's guess first but verify the guess by only parsing that particular
APKBUILD. If the subpackage/provides is in there we seem to have found it.

pmb/helpers/pmaports.py

@@ -155,6 +155,13 @@ def find(args, package, must_exist=True):
         if path:
             ret = os.path.dirname(path)
 
+        # Try to guess based on the subpackage name
+        guess = guess_main(args, package)
+        if guess:
+            # ... but see if we were right
+            if _find_package_in_apkbuild(args, package, f'{guess}/APKBUILD'):
+                ret = guess
+
         # Search in subpackages and provides
         if not ret:
             for path_current in _find_apkbuilds(args).values():
@@ -162,9 +169,9 @@ def find(args, package, must_exist=True):
                     ret = os.path.dirname(path_current)
                     break
 
-        # Guess a main package
+        # Use the guess otherwise
         if not ret:
-            ret = guess_main(args, package)
+            ret = guess
 
     # Crash when necessary
     if ret is None and must_exist: