[glib-networking] meson: improve GIO modules directory handling

[Michael Catanzaro <mcatanzaro src gnome org>]

commit bb6f8fc39d019e975b0f9ef272b99f8ffee464ce
Author: Tom Schoonjans <Tom Schoonjans diamond ac uk>
Date:   Thu Mar 15 13:30:20 2018 +0000

    meson: improve GIO modules directory handling
    
    An option was added to allow the user to install the GIO modules in a
    directory different than the one obtained from the gio pkg-config file.
    
    This patch is inspired by a recent commit in glib-openssl.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794358

 meson.build       |    5 ++++-
 meson_options.txt |    1 +
 2 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index 130d517..ca18472 100644
--- a/meson.build
+++ b/meson.build
@@ -46,7 +46,10 @@ endif
 glib_dep = dependency('glib-2.0', version: '>= 2.55.1')
 gio_dep = dependency('gio-2.0')
 
-gio_module_dir = gio_dep.get_pkgconfig_variable('giomoduledir')
+gio_module_dir = get_option('gio_module_dir')
+if gio_module_dir == ''
+  gio_module_dir = gio_dep.get_pkgconfig_variable('giomoduledir')
+endif
 assert(gio_module_dir != '', 'GIO_MODULE_DIR is missing from gio-2.0.pc')
 
 # *** Checks for LibProxy   ***
diff --git a/meson_options.txt b/meson_options.txt
index 1e04d19..3784c38 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -3,3 +3,4 @@ option('gnome_proxy_support', type: 'boolean', value: true, description: 'suppor
 option('pkcs11_support', type: 'boolean', value: true, description: 'support for PKCS#11 using p11-kit')
 option('installed_tests', type: 'boolean', value: false, description: 'enable installed tests')
 option('static_modules', type: 'boolean', value: false, description: 'build static modules')
+option('gio_module_dir', type: 'string', value: '', description: 'custom directory for GIO modules')