RFR: JDK-8055096: Remove explicit mx flag from javadoc command line

[Erik Joelsson]

Hello,

Please review this small patch. In Javadoc.gmk the javadoc command is 
defined with an explicit mx flag. However, configure is already 
calculating a suitable mx for a "large" java process, which is already 
provided in the JAVA variable. This patch removes the redundant mx flag 
from Javadoc.gmk.

Bug: https://bugs.openjdk.java.net/browse/JDK-8055096
Patch inline:

diff -r dbb964d72f25 make/Javadoc.gmk
--- a/make/Javadoc.gmk
+++ b/make/Javadoc.gmk
@@ -52,7 +52,6 @@
  BUILD_NUMBER=$(JDK_BUILD_NUMBER)

  JAVADOC_CMD = $(JAVA) \
-    -Xmx1024m \
      -Djava.awt.headless=true \
      $(NEW_JAVADOC) \
      -bootclasspath $(JDK_OUTPUTDIR)/classes

/Erik