Improve suspicious condition (string::find) message.

See forum thread:
https://sourceforge.net/apps/phpbb/cppcheck/viewtopic.php?f=3&t=192

lib/checkstl.cpp

@@ -764,7 +764,11 @@ void CheckStl::if_find()
 void CheckStl::if_findError(const Token *tok, bool str)
 {
     if (str)
-        reportError(tok, Severity::warning, "stlIfStrFind", "Suspicious condition. string::find will return 0 if the string is found at position 0. If this is what you want to check then string::compare is a faster alternative because it doesn't scan through the string.");
+        reportError(tok, Severity::warning, "stlIfStrFind",
+                    "Suspicious checking of string::find() return value.\n"
+                    "string::find will return 0 if the string is found at position 0. "
+                    "If that is wanted to check then string::compare is a faster alternative "
+                    "because it doesn't scan through the string.");
     else
         reportError(tok, Severity::warning, "stlIfFind", "Suspicious condition. The result of find is an iterator, but it is not properly checked.");
 }

test/teststl.cpp

@@ -1005,7 +1005,7 @@ private:
               "{\n"
               "    if (s.find(\"abc\")) { }\n"
               "}\n");
-        ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious condition. string::find will return 0 if the string is found at position 0. If this is what you want to check then string::compare is a faster alternative because it doesn't scan through the string.\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious checking of string::find() return value.\n", errout.str());
     }