Upgrade libxml2 and its portage dependencies

sys-libs/zlib/files/zlib-1.2.3-visibility-support.patch

Index: sys-libs/zlib/files/zlib-1.2.3-visibility-support.patch
diff --git a/sys-libs/zlib/files/zlib-1.2.3-visibility-support.patch b/sys-libs/zlib/files/zlib-1.2.3-visibility-support.patch
new file mode 100644
index 0000000000000000000000000000000000000000..ceb065e9c7bb90760757a59e33f27aff198f9226
--- /dev/null
+++ b/sys-libs/zlib/files/zlib-1.2.3-visibility-support.patch
@@ -0,0 +1,45 @@
+Only export symbols that should be exported.
+
+Patch by Mike Frysinger
+
+http://bugs.gentoo.org/32764
+http://bugs.gentoo.org/149929
+
+--- zlib-1.2.3/configure
++++ zlib-1.2.3/configure
+@@ -209,6 +209,20 @@
+ fi
+ 
+ cat > $test.c <<EOF
++int foo __attribute__ ((visibility ("hidden")));
++int main()
++{
++  return 0;
++}
++EOF
++if ($CC -c -fvisibility=hidden $CFLAGS $test.c) 2>/dev/null; then
++  CFLAGS="$CFLAGS -DHAS_attribute_visibility -fvisibility=hidden"
++  echo "Checking for attribute(visibility) support... Yes."
++else
++  echo "Checking for attribute(visibility) support... No."
++fi
++
++cat > $test.c <<EOF
+ #include <stdio.h>
+ #include <stdarg.h>
+ #include "zconf.h"
+--- zlib-1.2.3/zconf.in.h
++++ zlib-1.2.3/zconf.in.h
+@@ -244,7 +244,11 @@
+ #endif
+ 
+ #ifndef ZEXTERN
+-#  define ZEXTERN extern
++#  if defined(ZLIB_INTERNAL) && defined(HAS_attribute_visibility)
++#    define ZEXTERN extern __attribute__ ((visibility("default")))
++#  else
++#    define ZEXTERN extern
++#  endif
+ #endif
+ #ifndef ZEXPORT
+ #  define ZEXPORT