Build: increase gradle jvm heap size from 1 GB to 1.5 GB.

Author: stevenzwu

gradle.properties

@@ -32,4 +32,4 @@ org.gradle.parallel=true
 org.gradle.configureondemand=true
 # explicitly disable the configuration cache
 org.gradle.configuration-cache=false
-org.gradle.jvmargs=-Xmx1024m
+org.gradle.jvmargs=-Xmx1536m