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

Besides as as attribute the external can also be used as "type"

src/fortranscanner.l

@@ -255,7 +255,7 @@ NUM_TYPE  (complex|integer|logical|real)
 LOG_OPER  (\.and\.|\.eq\.|\.eqv\.|\.ge\.|\.gt\.|\.le\.|\.lt\.|\.ne\.|\.neqv\.|\.or\.|\.not\.)
 KIND      {ARGS}
 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}?)
+TYPE_SPEC (({NUM_TYPE}({BS}"*"{BS}[0-9]+)?)|({NUM_TYPE}{KIND})|EXTERNAL|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)