Config changes to support target_os="fuchsia"

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 6774b2a36b68419ac0e649da0b3292ff3e15647b..a02322a99df18a7a174d1783abfc2fb9dd40bc11 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -162,6 +162,8 @@ config("compiler") {
     configs += [ "//build/config/nacl:compiler" ]
   } else if (is_ios || is_mac) {
     configs += [ "//build/config/mac:compiler" ]
+  } else if (is_fuchsia) {
+    configs += [ "//build/config/fuchsia:compiler" ]
   }
 
   # See the definitions below.
@@ -294,7 +296,7 @@ config("compiler") {
 
   # Linux/Android common flags setup.
   # ---------------------------------
-  if (is_linux || is_android) {
+  if (is_linux || is_android || is_fuchsia) {
     if (use_pic) {
       cflags += [ "-fPIC" ]
       ldflags += [ "-fPIC" ]
@@ -324,7 +326,11 @@ config("compiler") {
           "-lpthread",
         ]
       }
-      ldflags += [ "-Wl,--as-needed" ]
+      if (!is_fuchsia) {
+        # We need mxio/magenta to get linked in, even if they're not directly
+        # referenced.
+        ldflags += [ "-Wl,--as-needed" ]
+      }
     }
   }