match whole word

* tool/transform_mjit_header.rb: add word boundary anchors and
  match whole word to get rid of false `static` declarations,
  e.g., rb_str_new_static.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62199 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/transform_mjit_header.rb

@@ -166,7 +166,7 @@ loop do
     extern_names << decl_name
     decl[match.begin(0)...match.end(0)] = ''
 
-    if decl =~ /static/
+    if decl =~ /\bstatic\b/
       STDERR.puts "warning: a static decl inside external definition of '#{decl_name}'"
     end