Remove some old cruft from rebar.config

I must've originally copied this config from Emonk.

rebar.config

@@ -1,12 +1,8 @@
 {port_specs, [{"priv/jiffy.so", ["c_src/*.c"]}]}.
 
 {port_env, [
-    %% Link the spidermonkey library
     {".*", "CFLAGS", "$CFLAGS -g -Wall"},
 
-    %% Make sure to link -lstdc++ on linux or solaris
-    {"(linux|solaris)", "LDFLAGS", "$LDFLAGS -lstdc++"},
-
     %% OS X Leopard flags for 64-bit
     {"darwin9.*-64$", "CXXFLAGS", "-m64"},
     {"darwin9.*-64$", "LDFLAGS", "-arch x86_64"},