add and use LDCOM environment variable

lib/rscons/builders/program.rb

@@ -7,6 +7,7 @@ module Rscons
       'LDFLAGS' => [],
       'LIBPATHS' => [],
       'LIBS' => [],
+      'LDCOM' => ['$LD', '-o', '$TARGET', '$LDFLAGS', '$SOURCES', '-L$[LIBPATHS]', '-l$[LIBS]']
     }
 
     def run(env, target, sources)
@@ -26,19 +27,12 @@ module Rscons
         end
       end
       unless Cache.open.up_to_date?(target, sources)
-        command = [
-          env['LD'] || env['CC'],
-          '-o', target,
-          *env['LDFLAGS'],
-          *sources,
-          *env['LIBPATHS'].map {|lp| "-L#{lp}"},
-          *env['LIBS'].map {|lib| "-l#{lib}"}
-        ]
         vars = {
           'TARGET' => target,
           'SOURCES' => sources,
+          'LD' => env['LD'] || env['CC'], # TODO: figure out whether to use CC or CXX
         }
-        env.execute("LINK #{target}", command, vars)
+        env.execute("LD #{target}", env['LDCOM'], vars)
         Cache.open.register_build(target, sources)
       end
       target