Issue29439: _decimal on Android requires linking with libm.
Patch by Chi Hsuan Yen.
diff --git a/setup.py b/setup.py
index d218722..f04bf22 100644
--- a/setup.py
+++ b/setup.py
@@ -2064,7 +2064,7 @@
                                                          'Modules',
                                                          '_decimal',
                                                          'libmpdec'))]
-            libraries = []
+            libraries = self.detect_math_libs()
             sources = [
               '_decimal/_decimal.c',
               '_decimal/libmpdec/basearith.c',