Support more special characters in file(STRINGS)

The commits "Teach Fortran compiler identification about the Portland
Group compiler" and "Fix previous change to file(STRINGS) command"
taught file(STRINGS) to recognize the form-feed '\f' character as part
of string literals.  The Portland Group Fortran compiler also puts 0x14
bytes at the end of string literals in some cases.  We generalize the
previous solution and add the new character in this commit.

Source/cmFileCommand.cxx

@@ -531,6 +531,13 @@ bool cmFileCommand::HandleStringsCommand(std::vector<std::string> const& args)
     return false;
     }
 
+  // At least one compiler (Portland Group Fortran) produces binaries
+  // with some extra characters in strings.
+  char extra[256]; // = {}; // some compilers do not like this
+  memset(extra, 0, sizeof(extra));
+  extra['\f'] = 1; // FF  (form feed)
+  extra[0x14] = 1; // DC4 (device control 4)
+
   // Parse strings out of the file.
   int output_size = 0;
   std::vector<std::string> strings;
@@ -585,7 +592,7 @@ bool cmFileCommand::HandleStringsCommand(std::vector<std::string> const& args)
       {
       // Ignore CR character to make output always have UNIX newlines.
       }
-    else if((c >= 0x20 && c < 0x7F) || c == '\t' || c == '\f' ||
+    else if((c >= 0x20 && c < 0x7F) || c == '\t' || extra[c] ||
             (c == '\n' && newline_consume))
       {
       // This is an ASCII character that may be part of a string.