Bug 634763 - Fortran: external subroutine as dummy argument not recognized

Besides as as attribute the external can also be used as "type"
Previous commit (pull request 121) was reverted (pull request 122) due to warning message.

src/fortranscanner.l

@@ -258,11 +258,12 @@ CHAR      (CHARACTER{ARGS}?|CHARACTER{BS}"*"({BS}[0-9]+|{ARGS}))
 TYPE_SPEC (({NUM_TYPE}({BS}"*"{BS}[0-9]+)?)|({NUM_TYPE}{KIND})|DOUBLE{BS}COMPLEX|DOUBLE{BS}PRECISION|{CHAR}|TYPE{ARGS}|CLASS{ARGS}|PROCEDURE{ARGS}?)
 
 INTENT_SPEC intent{BS}"("{BS}(in|out|in{BS}out){BS}")"
-ATTR_SPEC (ALLOCATABLE|DIMENSION{ARGS}|EXTERNAL|{INTENT_SPEC}|INTRINSIC|OPTIONAL|PARAMETER|POINTER|PROTECTED|PRIVATE|PUBLIC|SAVE|TARGET|NOPASS|PASS{ARGS}?|DEFERRED|NON_OVERRIDABLE)
+ATTR_SPEC (EXTERNAL|ALLOCATABLE|DIMENSION{ARGS}|{INTENT_SPEC}|INTRINSIC|OPTIONAL|PARAMETER|POINTER|PROTECTED|PRIVATE|PUBLIC|SAVE|TARGET|NOPASS|PASS{ARGS}?|DEFERRED|NON_OVERRIDABLE)
 ACCESS_SPEC (PRIVATE|PUBLIC)
 LANGUAGE_BIND_SPEC BIND{BS}"("{BS}C{BS}(,{BS}NAME{BS}"="{BS}"\""(.*)"\""{BS})?")"
 /* Assume that attribute statements are almost the same as attributes. */
 ATTR_STMT {ATTR_SPEC}|DIMENSION|{ACCESS_SPEC}
+EXTERNAL_STMT (EXTERNAL)
 
 CONTAINS  CONTAINS
 PREFIX    (RECURSIVE{BS_}|IMPURE{BS_}|PURE{BS_}|ELEMENTAL{BS_}){0,3}(RECURSIVE|IMPURE|PURE|ELEMENTAL)?
@@ -726,6 +727,18 @@ private                                 {
 					  }
 					}
   */
+{EXTERNAL_STMT}/({BS}"::"|{BS_}{ID})   { 
+                                          /* external can be a "type" or an attribute */
+                                          if(YY_START == Start)
+                                          {
+                                            addModule(NULL); 
+                                            yy_push_state(ModuleBody); //anon program
+                                          }
+                                          QCString tmp = yytext;
+                                          currentModifiers |= tmp.stripWhiteSpace();
+					  argType = QCString(yytext).simplifyWhiteSpace().lower();
+					  yy_push_state(AttributeList);
+  				       }
 {ATTR_STMT}/{BS_}{ID}		       |
 {ATTR_STMT}/{BS}"::"                   { 
                                           /* attribute statement starts */
@@ -744,7 +757,7 @@ private                                 {
 <AttributeList>{
 {COMMA}					{}
 {BS}					{}
-{ATTR_SPEC}.				{ /* update current modifierswhen it is an ATTR_SPEC and not a variable name */
+{ATTR_SPEC}.				{ /* update current modifiers when it is an ATTR_SPEC and not a variable name */
             				  /* bug_625519 */
                                           QChar chr = yytext[(int)yyleng-1];
                                           if (chr.isLetter() || chr.isDigit() || (chr == '_'))
@@ -1723,8 +1736,11 @@ static QCString applyModifiers(QCString typeName, SymbolModifiers& mdfs)
   }
   if (mdfs.external) 
   {
-    if (!typeName.isEmpty()) typeName += ", ";
-    typeName += "external";
+    if (!typeName.contains("external"))
+    {
+      if (!typeName.isEmpty()) typeName += ", ";
+      typeName += "external";
+    }
   }
   if (mdfs.intrinsic) 
   {