Linux: add gyp rules for gio library and gsettings link mode.

build/linux/system.gyp

Index: build/linux/system.gyp
===================================================================
--- build/linux/system.gyp	(revision 85385)
+++ build/linux/system.gyp	(working copy)
@@ -212,6 +212,41 @@
       }]]
     },
     {
+      'target_name': 'gio',
+      'type': 'settings',
+      'conditions': [
+        ['use_gio==1 and _toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags gio-2.0)',
+            ],
+            'defines': [
+              'USE_GIO',
+            ],
+            'conditions': [
+              ['linux_link_gsettings==0', {
+                'defines': ['DLOPEN_GSETTINGS'],

[Paweł Hajdan Jr., 2011/05/16 05:56:34]

I'm somewhat worried about this difference in names: the target is named gio, we
have use_gio gyp switch and USE_GIO cpp symbol, but then there's
linux_link_gsettings gyp flag and DLOPEN_GSETTINGS cpp symbol.

Does it make sense to unify those two? It's not a very big concern for me (I
don't know those libraries, so maybe the names make more sense that way), but if
there are no reasons to do otherwise, more consistent names should help
packagers.

[Mike Mammarella, 2011/05/16 06:08:13]

Yeah, I thought about this, and wondered if I should make a separate gsettings
target that depends on the gio target and has the gsettings-specific stuff. In
the end I think this is a little simpler though.

The library itself is called gio, but the gsettings API within it was added more
recently than the minimum version we depend on (hence the dlopen stuff in the
first place). The gio library is also already used (indirectly) via some other
library we already depend on, so I didn't want to imply that everything in gio
would be accessed via dlsym.

+              }],
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(<(pkg-config) --libs-only-L --libs-only-other gio-2.0)',
+            ],
+            'libraries': [
+              '<!@(<(pkg-config) --libs-only-l gio-2.0)',
+            ],
+            'conditions': [
+              ['linux_link_gsettings==0', {
+                'libraries': [
+                  '-ldl',
+                ],
+              }],
+            ],
+          },
+      }]]
+    },
+    {
       'target_name': 'x11',
       'type': 'settings',
       'conditions': [