Remove usage of 'parent' module.

Although 'parent' is a core Perl module, it is not installed by default
on Fedora. :( :(

kdesrc-build

@@ -4503,7 +4503,7 @@ EOF
 
     # This is a module used to support configuring with autotools.
 
-    use parent -norequire, 'GenericBuildSystem';
+    our @ISA = ('GenericBuildSystem');
 
     ksb::Debug->import();
     ksb::Util->import();
@@ -4551,7 +4551,7 @@ EOF
     # This is a module used to do only one thing: Bootstrap CMake onto a system
     # that doesn't have it, or has only an older version of it.
 
-    use parent -norequire, 'GenericBuildSystem';
+    our @ISA = ('GenericBuildSystem');
 
     ksb::Debug->import();
     ksb::Util->import();