Add YouCompleteMe support

YouCompleteMe[1] is a vim plugin that implements semantic
code completion using libclang.

For non-trivial projects such as libvirt, the plugin needs
some help figuring out where to find the various header
files: generate its configuration file at configure time
so that the plugin works out of the box.

[1] http://valloric.github.io/YouCompleteMe/

.gitignore

@@ -36,6 +36,7 @@
 .lvimrc
 .memdump
 .sc-start-sc_*
+.ycm_extra_conf.py
 /ABOUT-NLS
 /AUTHORS
 /ChangeLog

.ycm_extra_conf.py.in

+flags = [
+  '-I@abs_top_builddir@',
+  '-I@abs_top_srcdir@',
+  '-I@abs_top_builddir@/gnulib/lib',
+  '-I@abs_top_srcdir@/gnulib/lib',
+  '-I@abs_top_builddir@/include',
+  '-I@abs_top_srcdir@/include',
+  '-I@abs_top_builddir@/src',
+  '-I@abs_top_srcdir@/src',
+  '-I@abs_top_builddir@/src/access',
+  '-I@abs_top_srcdir@/src/access',
+  '-I@abs_top_builddir@/src/admin',
+  '-I@abs_top_srcdir@/src/admin',
+  '-I@abs_top_builddir@/src/bhyve',
+  '-I@abs_top_srcdir@/src/bhyve',
+  '-I@abs_top_builddir@/src/conf',
+  '-I@abs_top_srcdir@/src/conf',
+  '-I@abs_top_builddir@/src/libxl',
+  '-I@abs_top_srcdir@/src/libxl',
+  '-I@abs_top_builddir@/src/locking',
+  '-I@abs_top_srcdir@/src/locking',
+  '-I@abs_top_builddir@/src/logging',
+  '-I@abs_top_srcdir@/src/logging',
+  '-I@abs_top_builddir@/src/lxc',
+  '-I@abs_top_srcdir@/src/lxc',
+  '-I@abs_top_builddir@/src/qemu',
+  '-I@abs_top_srcdir@/src/qemu',
+  '-I@abs_top_builddir@/src/remote',
+  '-I@abs_top_srcdir@/src/remote',
+  '-I@abs_top_builddir@/src/rpc',
+  '-I@abs_top_srcdir@/src/rpc',
+  '-I@abs_top_builddir@/src/secret',
+  '-I@abs_top_srcdir@/src/secret',
+  '-I@abs_top_builddir@/src/security',
+  '-I@abs_top_srcdir@/src/security',
+  '-I@abs_top_builddir@/src/util',
+  '-I@abs_top_srcdir@/src/util',
+  '-I@abs_top_builddir@/src/vmx',
+  '-I@abs_top_srcdir@/src/vmx',
+  '-I@abs_top_builddir@/src/xenconfig',
+  '-I@abs_top_srcdir@/src/xenconfig',
+]
+
+def FlagsForFile(filename, **kwargs):
+  return { 'flags': flags, 'do_cache': True }

configure.ac

@@ -883,6 +883,7 @@ AC_CONFIG_FILES([\
         gnulib/lib/Makefile \
         gnulib/tests/Makefile \
         .color_coded \
+        .ycm_extra_conf.py \
         libvirt.pc \
         libvirt-qemu.pc \
         libvirt-lxc.pc \