android/build.py: add parameter that specifies a subdirectory

android/build.py

@@ -127,11 +127,15 @@ def download_tarball(url, md5):
 
 class Project:
     def __init__(self, url, md5, installed, name=None, version=None,
+                 base=None,
                  use_cxx=False, use_clang=False):
+        if base is None:
             basename = os.path.basename(url)
             m = re.match(r'^(.+)\.(tar(\.(gz|bz2|xz|lzma))?|zip)$', basename)
             if not m: raise
             self.base = m.group(1)
+        else:
+            self.base = base
 
         if name is None or version is None:
             m = re.match(r'^([-\w]+)-(\d[\d.]*[a-z]?)$', self.base)