Stop using namespace std.

The pattern of #include and using namespace std here fails to build
with GCC. At first glance it's a GCC bug rather than libc++ doing
something wrong. Regardless, it can be worked around by just
specifying std:: where appropriate.

Bug: 19606303
Change-Id: I5652682eae7ca7559cf2a9307909859013440781
diff --git a/tools/aapt/Images.cpp b/tools/aapt/Images.cpp
index 5ab177b..063b4e6 100644
--- a/tools/aapt/Images.cpp
+++ b/tools/aapt/Images.cpp
@@ -481,8 +481,9 @@
 
     // assuming the image is a round rect, compute the radius by marching
     // diagonally from the top left corner towards the center
-    image->outlineAlpha = max(max_alpha_over_row(image->rows[innerMidY], innerStartX, innerEndX),
-            max_alpha_over_col(image->rows, innerMidX, innerStartY, innerStartY));
+    image->outlineAlpha = std::max(
+        max_alpha_over_row(image->rows[innerMidY], innerStartX, innerEndX),
+        max_alpha_over_col(image->rows, innerMidX, innerStartY, innerStartY));
 
     int diagonalInset = 0;
     find_max_opacity(image->rows, innerStartX, innerStartY, innerMidX, innerMidY, 1, 1,