Use relative path in -L and -Wl,-rpath-link

build/config/posix/BUILD.gn

Index: build/config/posix/BUILD.gn
diff --git a/build/config/posix/BUILD.gn b/build/config/posix/BUILD.gn
index 11cad83d0755bdf1bd448c63355f422942fef144..057efb82a19e4de1127705f788ce841c0aa56c05 100644
--- a/build/config/posix/BUILD.gn
+++ b/build/config/posix/BUILD.gn
@@ -25,12 +25,19 @@ config("runtime_library") {
     ldflags = cflags
 
     # Need to get some linker flags out of the sysroot.
-    ldflags += exec_script("sysroot_ld_path.py",
+    ld_paths = exec_script("sysroot_ld_path.py",
                            [
                              rebase_path("//build/linux/sysroot_ld_path.sh",
                                          root_build_dir),
                              rebase_path(sysroot),
                            ],
                            "list lines")
+    foreach(ld_path, ld_paths) {
+      ld_path = rebase_path(ld_path, root_build_dir)
+      ldflags += [
+        "-L" + ld_path,
+        "-Wl,-rpath-link=" + ld_path,
+      ]
+    }
   }
 }