Log Message:
Update libxml2 to 2.9.4.

Pkgsrc changes:
 * Add some casts to match types and format strings, plus
   fix value range of toupper() operation.
 * Merge patch-ag into the new patch-encoding.c.
 * Add comments to existing patches which lacked comments.

Upstream changes to libxml2-2.9.4: May 23 2016

Security:

   CVE-2016-3627 Avoid building recursive entities
   CVE-2016-1833 Heap-based buffer overread in htmlCurrentChar
   CVE-2016-1835 Heap use-after-free in xmlSAX2AttributeNs
   CVE-2016-1837 Heap use-after-free in htmlParsePubidLiteral
   	      	 and htmlParseSystemiteral
   CVE-2016-1836 Bug 759398: Heap use-after-free in xmlDictComputeFastKey
   CVE-2016-1839 Bug 758605: Heap-based buffer overread in xmlDictAddString
   CVE-2016-1838 Bug 758588: Heap-based buffer overread in
	      	 xmlParserPrintFileContextInternal
   CVE-2016-1840 Bug 757711: heap-buffer-overflow in xmlFAParsePosCharGroup
   CVE-2016-4483 Avoid an out of bound access when serializing
   		 malformed strings
   CVE-2016-1834 Bug 763071: heap-buffer-overflow in xmlStrncat
   CVE-2016-3705 Add missing increments of recursion depth counter to
   		 XML parser.
   CVE-2016-1762 Heap-based buffer overread in xmlNextChar

   More format string warnings with possible format string vulnerability
   Heap-based buffer-underreads due to xmlParseName
   Fix some format string warnings with possible format string vulnerability
   Unsigned addition may overflow in xmlMallocAtomicLoc()

Other bugfixes:

   Detect change of encoding when parsing HTML names
   Fix inappropriate fetch of entities content
   Correct the usage of LDFLAGS
   Revert the use of SAVE_LDFLAGS in configure.ac
   libxml2 hardcodes -L/lib in zlib/lzma tests which breaks cross-compiles
   Add more debugging info to runtest
   Implement "runtest -u" mode
   Integer signed/unsigned type mismatch in xmlParserInputGrow()
   Integer overflow parsing port number in URI
   Fix apibuild for a recently added constructv2.9.4-rc2
   Use pkg-config to locate zlib when possible
   Use pkg-config to locate ICU when possible
   Fix an error with regexp on nullable counted char transition
   Fix memory leak with XPath namespace nodes
   Fix namespace axis traversal
   Add a make rule to rebuild for ASAN
   Fix null pointer deref in docs with no root element
   Portability to non C99 compliant compilers
   dict.h: Move xmlDictPtr definition before includes to allow direct
     inclusion.
   Fix XSD validation of URIs with ampersands
   xmlschemastypes.c: accept endOfDayFrag Times set to "24:00:00" mean
     "end of day" and should not cause an error. v2.9.4-rc1
   os400: tell about xmllint and xmlcatalog in README400.
   os400: properly process SGML add in XMLCATALOG command.
   os400: implement CL command XMLCATALOG.
   os400: compile and install program xmlcatalog (qshell-only).
   xmlcatalog: flush stdout before interactive shell input.
   os400: expand tabs in sources, strip trailing blanks.
   os400: implement CL command XMLLINT.
   os400: compile and install program xmllint (qshell-only).
   os400: initscript make_module(): Use options instead of
     positional parameters.
   xmllint: flush stdout before interactive shell input.
   os400: c14n.rpgle: allow *omit for nullable reference parameters.
   os400: use like() for double type.
   os400: use like() for int type.
   os400: use like() for unsigned int type.
   os400: use like() for enum types.
   Add xz to xml2-config --libs output
   Don't recurse into OP_VALUEs in xmlXPathOptimizeExpression
   Fix namespace::node() XPath expression
   Fix OOB write in xmlXPathEmptyNodeSet
   Fix parsing of NCNames in XPath
   Fix OOB read with invalid UTF-8 in xmlUTF8Strsize
   Do normalize string-based datatype value in RelaxNG facet checking
   Fix typo: s{ ec -> cr }cipt
   Fix typos: dictio{ nn -> n }ar{y,ies}
   Fix typos: PATH_{ SEAPARATOR -> SEPARATOR }
   Correct a typo.
   Bug 760921: REGRESSION (8eb55d78): doc/examples/io1 test fails after fix
     for "xmlSaveUri() incorrectly recomposes URIs with rootless paths"
   Bug 760861: REGRESSION (bf9c1dad): Missing results for
     test/schemas/regexp-char-ref_[01].xsd
   error.c: *input->cur == 0 does not mean no error
   Add missing RNG test files
   Bug 760190: configure.ac should be able to build --with-icu without
     icu-config tool
   Bug 760183: REGRESSION (v2.9.3): XML push parser fails with bogus
     UTF-8 encoding error when multi-byte character in large CDATA
     section is split across buffer
   Bug 758572: ASAN crash in make check
   Bug 721158: Missing ICU string when doing --version on xmllint
   python 3: libxml2.c wrappers create Unicode str already
   win32\VC10\config.h and VS 2015
   Add autogen.sh to distrib
   Add configure maintainer mode