[applocal.py] Don't try to install dependencies not managed by vcpkg (#16716)

This fixes build failures on osx when using dependencies not coming
from vcpkg (e.g. closed binaries). vcpkg tried to install those
dependencies (which fails because they're not where vcpkg expects them).

Fixes issue #8203

Co-authored-by: Martijn Otto <git@martijnotto.nl>

scripts/buildsystems/osx/applocal.py

@@ -259,6 +259,11 @@ def fix_dependency(binary, dep):
     else:
         return True
 
+    # if the source path doesn't exist it's probably not a dependency
+    # originating with vcpkg and we should leave it alone
+    if not os.path.exists(qtnamesrc):
+        return True
+
     dep_ok = True
     # check that rpath of 'dep' inside binary has been correctly set
     # (ie: relative to exepath using '@executable_path' syntax)