build: support dtrace on ARM

Use the same dtrace command on ARM as on i386. Patch obtained from
FreeBSD PR 218081 [1].

1. https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218081

PR-URL: #12193
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: bradleythughes

node.gyp

@@ -488,7 +488,7 @@
                 '<(OBJ_DIR)/node/src/node_dtrace_ustack.o'
               ],
               'conditions': [
-                [ 'target_arch=="ia32"', {
+                [ 'target_arch=="ia32" or target_arch=="arm"', {
                   'action': [
                     'dtrace', '-32', '-I<(SHARED_INTERMEDIATE_DIR)', '-Isrc',
                     '-C', '-G', '-s', 'src/v8ustack.d', '-o', '<@(_outputs)',