meson: Use implicit dependencies for required dependencies.

The generated pkgconfig file for the library is incomplete, since application,
such as cog, only explicity depend on WPEBackend-fdo, though it also depends on
libwpe. It has not been a problem since wpe-webkit-1.0.pc explicity expose
libwpe requirement. Still, for robustness and self documentation, it's better to
express that dependency explicity too.

Also, this patch removes the pkg config version declation since it's also
handled implicitly by meson.

Previous pc file:

prefix=/usr
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include

Name: wpebackend-fdo-1.0
Description: The WPEBackend-fdo library
Version: 1.9.91
Libs: -L${libdir} -lWPEBackend-fdo-1.0
Cflags: -I${includedir}/wpe-fdo-1.0

New pc file:

prefix=/usr/local
libdir=${prefix}/lib
includedir=${prefix}/include

Name: wpebackend-fdo-1.0
Description: The WPEBackend-fdo library
Version: 1.9.1
Requires: wpe-1.0
Requires.private: xkbcommon, egl
Libs: -L${libdir} -lWPEBackend-fdo-1.0
Libs.private: -ldl
Cflags: -I${includedir}/wpe-fdo-1.0

meson.build

@@ -254,13 +254,15 @@ add_project_arguments(
 	language: 'c'
 )
 
+wpe_dep = dependency('wpe-1.0', version: '>=1.6.0', fallback: ['libwpe', 'libwpe_dep'])
+
 deps = [
 	dependency('epoxy'),
 	dependency('gio-2.0'),
 	dependency('gobject-2.0'),
 	dependency('wayland-client'),
 	dependency('wayland-server'),
-	dependency('wpe-1.0', version: '>=1.6.0', fallback: ['libwpe', 'libwpe_dep']),
+        wpe_dep,
 ]
 
 # Will be set to the library dependency which provides the wl_egl_* functions.
@@ -348,8 +350,7 @@ import('pkgconfig').generate(
 	description: 'The WPEBackend-fdo library',
 	name: 'wpebackend-fdo-' + api_version,
 	subdirs: 'wpe-fdo-' + api_version,
-	libraries: lib,
-	version: meson.project_version(),
+	libraries: [lib, wpe_dep],
 )
 
 if get_option('build_docs')