Remove default argument from "C" API.

This is far from the only C incompatibility in this file, but it's the
one that's most likely to not break builds, so I'm starting small.

This is a source compat break, but not an ABI break.

Bug: android/ndk#1920
Test: treehugger
Change-Id: I5a32762fa61b1399fb354397479603858184ea05

Author: DanAlbert

include/android/surface_control.h

@@ -346,7 +346,7 @@ void ASurfaceTransaction_setZOrder(ASurfaceTransaction* transaction,
  */
 void ASurfaceTransaction_setBuffer(ASurfaceTransaction* transaction,
                                    ASurfaceControl* surface_control, AHardwareBuffer* buffer,
-                                   int acquire_fence_fd = -1) __INTRODUCED_IN(29);
+                                   int acquire_fence_fd) __INTRODUCED_IN(29);
 
 /**
  * Updates the color for \a surface_control.  This will make the background color for the