[gfortran,patch] Handle "%3$d"-style format specifiers in error.c

[FX Coudert]

> Hmm -- perhaps I should have been clearer that my "this otherwise  
> looks ok to me" couldn't count as a formal review, because I'm not  
> a maintainer?  If so, my apologies.

Sorry for not being clearer myself. We (the listed gfortran  
maintainers) try to review patches, but we indeed have a right to  
check in our own patches. I felt that, with the detailed review you  
made, and the testing done, the patch was sufficiently safe to commit  
without requiring someone else to look at it.

Thanks again,
FX