Fix mac linking problem (#38)

We had is_component_build = false before it was erroneously
removed in f62b338

.gn

@@ -25,6 +25,7 @@ default_args = {
   is_cfi = false
   use_dummy_lastchange = true
   treat_warnings_as_errors = true
+
   # https://cs.chromium.org/chromium/src/docs/ccache_mac.md
   clang_use_chrome_plugins = false
   v8_enable_gdbjit = false
@@ -36,7 +37,12 @@ default_args = {
   v8_use_external_startup_data = false
   v8_use_snapshot = true
   v8_postmortem_support = true  # for https://github.com/nodejs/llnode/
+
   # We don't want to require downloading the binary executable
   # tools/clang/dsymutil.
   enable_dsyms = false
+
+  # TODO(ry) Remove this so debug builds can link faster. Currently removing
+  # this breaks cargo build in debug mode in OSX.
+  is_component_build = false
 }