Plumb system_libdir variable from GN to pkg-config.py

build/config/linux/pkg_config.gni

Index: build/config/linux/pkg_config.gni
diff --git a/build/config/linux/pkg_config.gni b/build/config/linux/pkg_config.gni
index 914ca8d6e728ae8eb3826e760246c6561fe28df6..a1adc9ecc851d44c7120e1aafeb18713d5ab1889 100644
--- a/build/config/linux/pkg_config.gni
+++ b/build/config/linux/pkg_config.gni
@@ -31,6 +31,10 @@ declare_args() {
   # Leaving it blank defaults to searching PATH for 'pkg-config' and relying on
   # the sysroot mechanism to find the right .pc files.
   pkg_config = ""
+
+  # CrOS builds set the `system_libdir` variable as part of building on a 64 or

[brettw, 2016/01/07 00:43:25]

I'm a bit confused what "lib" is relative to. The root directory? The sysroot?
It would be goot to mention that here an in the python script.

[rjkroege, 2016/01/07 01:37:37]

Done. Much more detailed comment now.

+  # 32 bit target.
+  system_libdir = "lib"
 }
 
 pkg_config_script = "//build/config/linux/pkg-config.py"
@@ -44,11 +48,15 @@ if (sysroot != "") {
     sysroot,
     "-a",
     current_cpu,
+    "--system_libdir",
+    system_libdir,
   ]
 } else if (pkg_config != "") {
   pkg_config_args = [
     "-p",
     pkg_config,
+    "--system_libdir",
+    system_libdir,
   ]
 } else {
   pkg_config_args = []