Fix build-time pkg-config files in VPATH

The pkg-config files in src/ make it pretty easy to build language
bindings against an uninstalled libvirt, however, they don't work with
VPATH builds. The reason is that all *-api.xml files are generated in
source rather than build directory.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

src/libvirt-lxc.pc.in

@@ -6,7 +6,7 @@ prefix=@abs_top_builddir@
 exec_prefix=@abs_top_builddir@
 libdir=@abs_top_builddir@/src/.libs
 includedir=@abs_top_builddir@/include
-datarootdir=@abs_top_builddir@
+datarootdir=@abs_top_srcdir@
 
 libvirt_lxc_api=@datadir@/docs/libvirt-lxc-api.xml
 

src/libvirt-qemu.pc.in

@@ -6,7 +6,7 @@ prefix=@abs_top_builddir@
 exec_prefix=@abs_top_builddir@
 libdir=@abs_top_builddir@/src/.libs
 includedir=@abs_top_builddir@/include
-datarootdir=@abs_top_builddir@
+datarootdir=@abs_top_srcdir@
 
 libvirt_qemu_api=@datadir@/docs/libvirt-qemu-api.xml
 

src/libvirt.pc.in

@@ -6,7 +6,7 @@ prefix=@abs_top_builddir@
 exec_prefix=@abs_top_builddir@
 libdir=@abs_top_builddir@/src/.libs
 includedir=@abs_top_builddir@/include
-datarootdir=@abs_top_builddir@
+datarootdir=@abs_top_srcdir@
 
 libvirt_api=@datadir@/docs/libvirt-api.xml