libmxml: upgrade 4.0.5 -> 4.0.6

Changelog:
https://github.com/michaelrsweet/mxml/releases/tag/v4.0.6

Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-oe/recipes-support/libmxml/libmxml_4.0.6.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;branch=master;protocol=https;tag=v${PV}"
-SRCREV = "18d5c7dd9c71ebc1d3f21fe1e0614300babdda84"
+SRCREV = "874e249a0d3b506e883210b7ceece5316a8489d4"
 
 # Package does not support out of tree builds.
 inherit autotools-brokensep