build: unbreak -prof, disable PIE on OS X

Commit 204f3a8 ("build: Bump MACOSX_DEPLOYMENT_TARGET to 10.7")
unwittingly turned on new ASLR features that make `-prof` unusable for
profiling C++ code, breaking `test/parallel/test-tick-processor.js` in
the process.  Build with `-Wl,-no_pie` for now.

Fixes: https://github.com/nodejs/node/issues/5903
PR-URL: https://github.com/nodejs/node/pull/6453
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

common.gypi

@@ -325,7 +325,12 @@
         },
         'target_conditions': [
           ['_type!="static_library"', {
-            'xcode_settings': {'OTHER_LDFLAGS': ['-Wl,-search_paths_first']},
+            'xcode_settings': {
+              'OTHER_LDFLAGS': [
+                '-Wl,-no_pie',
+                '-Wl,-search_paths_first',
+              ],
+            },
           }],
         ],
         'conditions': [