libmxml: upgrade 3.2 -> 3.3

mxml 3.3 is a bug fix release. Changes include:

  - Cleaned up usage of free throughout the library
  - Added more error handling to the library
  - Fixed potential memory leak in mxmlLoad* functions
  - Fixed mxmlSaveString with a buffer size of 0
  - Fixed MXML_MINOR_VERSION value in "mxml.h"
  - Fixed POSIX threading support for MingW
  - Fixed some minor memory leaks found by Coverity.

Signed-off-by: Pierre-Jean Texier <pierre-jean.texier@lafon.fr>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-support/libmxml/libmxml_3.3.bb

@@ -5,7 +5,7 @@ HOMEPAGE = "https://www.msweet.org/mxml/"
 BUGTRACKER = "https://github.com/michaelrsweet/mxml/issues"
 
 SRC_URI = "git://github.com/michaelrsweet/mxml.git;nobranch=1;protocol=https"
-SRCREV = "38b044ed8ca2a611ed9ed3e26c4b46416335194e"
+SRCREV = "0237559fdbcecae34157b547aa2b99e12de305a2"
 S = "${WORKDIR}/git"
 
 inherit autotools