[Patch, fortran] Fix PR19101 missing & in character continuation not caught

[Paul Thomas]

Steve,

>IMHO, it is an error to use a tab.  As I stated, -fno-tabs or
>-pedantic or -std=f95 are the only options that will trigger
>the error.
>  
>
True enough; especially on the options.....

>Your suggestion also doesn't handle the problem with fixed-form
>source code with a tab in column 1.  My current patch deals with
>tab in fixed-form and free-form code in an almost consistent 
>manor (ie., the error messages are slightly different in that 
>a locus can be reported for free-form).
>
.....again true.

I have to agree with your original title. I just tracked down a 
regression to a tab that appeared in an error message.

OK by me but give it 24 hours for any further opinions, please.

Paul