configure libxml2 with pkg-config

[Lawrence Rust <lvr@…>]

commit f6a46a055568da1bdf789464a428b7384524b561 added a configure time check for libxml2 (used by libmythbluray) which is enabled by default and has a hardcoded default include path. This requires cross compiling systems (Linux->Windows) without target libxml2 to be aware of the configure script version and disable libxml2. A more elegant solution would be to use pkg-config:

if [ enabled libxml2 ]; then
  if [ pkg-config --exists libxml-2.0 ]; then
    libxml2_path_default=`pkg-config --cflags libxml-2.0`
  else
    disable libxml2
  fi
fi

[robertm]

Lawrence,

Thanks. Please attach as a patch/diff and I'll take care of it.

[Lawrence Rust <lvr@…>]

Patch attached.

Also included is a small patch to detect Intel i3 & i5 CPUs and select core2 optimisation when --cpu=host is specified.

[robertm]

Hi Lawrence,

Go ahead and open a separate ticket for the unrelated processor patch, please, as Janne will need to okay that one.

Thanks.

[Lawrence Rust <lvr@…>]

OK, but an afterthought.

---    if pkg-config --exists libxml-2.0 ; then
+++    if which pkg-config >/dev/null 2>&1 && pkg-config --exists libxml-2.0 ; then

[Lawrence Rust <lvr@…>]

Just found a minor problem. The output of pkg-config has a trailing space which is passed onto gcc as an include path and so gcc fails to find the xml headers. Need to massage the output to remove the trailing space:

+ libxml2_path=pkg-config --cflags-only-I libxml-2.0|sed -n "s/-I\([^ ]*\) *$/\1/p"

[robertm]

Fixed in 52c9e68.

[Robert McNamara]

Update configure script to use pkg-config to check for libxml2.

Patch from Lawrence Rust, I opted not to use a later amendment that had some syntax errors (and we presume that pkg-config is there and working elsewhere in configure anyway).

Fixes #9442.

Changeset: 52c9e684583f4b2cd15693572e48e37d3c70887a