Increase the Java heap size for droiddoc

Increasing the Java heap for droiddoc generation from 768 to 1280
megabytes reduces build times by about 2-3 minutes. For fast
build servers this can reduce build times by around 30%. For
slower workstation class machines the build is reduced with no
other obvious undesirable side effects.

Change-Id: I4ff04318ae78fc7b5a5a0499bacfc5527e966ff6
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index 87576dc..60b9c83 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -163,7 +163,7 @@
 		LD_LIBRARY_PATH=$(HOST_OUT_SHARED_LIBRARIES) \
 		javadoc \
                 \@$(PRIVATE_SRC_LIST_FILE) \
-                -J-Xmx768m \
+                -J-Xmx1280m \
                 -J-Djava.library.path=$(HOST_OUT_SHARED_LIBRARIES) \
                 $(PRIVATE_PROFILING_OPTIONS) \
                 -quiet \