[wscript] Fix FTBFS with -Wl,--as-needed

Patch by Adam Conrad <adconrad@canonical.com>, taken from Ubuntu's
jackd2 package.

Fixes linkage errors as described in

   http://permalink.gmane.org/gmane.comp.audio.jackit/25841

example-clients/wscript

@@ -86,10 +86,9 @@ def build(bld):
             #prog.env.append_value("LINKFLAGS", "-arch i386 -arch ppc -arch x86_64")
             prog.env.append_value("LINKFLAGS", "")
         if bld.env['IS_LINUX']:
-            prog.use += ['RT']
-            prog.env.append_value("LINKFLAGS", "-lm")
+            prog.use += ['RT', 'M']
         if bld.env['IS_SUN']:
-            prog.env.append_value("LINKFLAGS", "-lm")
+            prog.use += ['M']
 
         prog.target = example_program
    

linux/wscript

@@ -38,9 +38,9 @@ def build(bld):
         jackd.use = ['serverlib']
         if bld.env['IS_LINUX'] and bld.env['BUILD_JACKDBUS']: 
             jackd.source += ['../dbus/reserve.c', '../dbus/audio_reserve.c'] 
-            jackd.use += ['PTHREAD', 'DL', 'RT', 'DBUS-1']
+            jackd.use += ['PTHREAD', 'DL', 'RT', 'M', 'STDC++', 'DBUS-1']
         else:
-            jackd.use += ['PTHREAD', 'DL', 'RT']
+            jackd.use += ['PTHREAD', 'DL', 'RT', 'M', 'STDC++']
         jackd.target = 'jackd'
   	
     create_jack_driver_obj(bld, 'dummy', '../common/JackDummyDriver.cpp')

wscript

@@ -183,6 +183,8 @@ def configure(conf):
     conf.env['LIB_PTHREAD'] = ['pthread']
     conf.env['LIB_DL'] = ['dl']
     conf.env['LIB_RT'] = ['rt']
+    conf.env['LIB_M'] = ['m']
+    conf.env['LIB_STDC++'] = ['stdc++']
     conf.env['JACK_API_VERSION'] = JACK_API_VERSION
     conf.env['JACK_VERSION'] = VERSION
 
@@ -235,8 +237,6 @@ def configure(conf):
         if m != None:
             svnrev = m.group(1)
 
-    conf.env.append_unique('LINKFLAGS', ['-lm', '-lstdc++'])
-
     if Options.options.mixed == True:
         env_variant2 = conf.env.copy()
         conf.set_env_name('lib32', env_variant2)