Move prefix_in_list to the single location where it is used

This makes the `goto_cc_cmdlinet` class easier to follow because it can
be read without seeing this special case for `armcc`.

Author: thomasspriggs

src/goto-cc/armcc_cmdline.cpp

@@ -265,6 +265,21 @@ static const char *options_with_arg[]=
   nullptr
 };
 
+static bool
+prefix_in_list(const char *option, const char **list, std::string &prefix)
+{
+  for(std::size_t i = 0; list[i] != nullptr; i++)
+  {
+    if(strncmp(option, list[i], strlen(list[i])) == 0)
+    {
+      prefix = std::string(list[i]);
+      return true;
+    }
+  }
+
+  return false;
+}
+
 bool armcc_cmdlinet::parse(int argc, const char **argv)
 {
   for(int i=1; i<argc; i++)

src/goto-cc/goto_cc_cmdline.cpp

@@ -46,23 +46,6 @@ bool goto_cc_cmdlinet::in_list(const char *option, const char **list)
   return false;
 }
 
-bool goto_cc_cmdlinet::prefix_in_list(
-  const char *option,
-  const char **list,
-  std::string &prefix)
-{
-  for(std::size_t i=0; list[i]!=nullptr; i++)
-  {
-    if(strncmp(option, list[i], strlen(list[i]))==0)
-    {
-      prefix=std::string(list[i]);
-      return true;
-    }
-  }
-
-  return false;
-}
-
 std::size_t goto_cc_cmdlinet::get_optnr(const std::string &opt_string)
 {
   optionalt<std::size_t> optnr;

src/goto-cc/goto_cc_cmdline.h

@@ -26,11 +26,6 @@ class goto_cc_cmdlinet:public cmdlinet
 
   static bool in_list(const char *option, const char **list);
 
-  static bool prefix_in_list(
-    const char *option,
-    const char **list,
-    std::string &prefix);
-
   // never fails, will add if not found
   std::size_t get_optnr(const std::string &option);