bug#54817: Outdated IBM XL Fortran shared library work around

[William T Jones]

Hello,

Libtool 2.4.6 has an apparently outdated work around for the IBM XL 
Fortran compiler's inability to link shared libraries (see m4/libtool.m4 
lines 5208, 5237-5248).

As comments in m4/libtool.m4 state, the problem is with IBM XL Fortran 
version 10.1 on PowerPC.  However, we are now using IBM XL Fortran 
version 16.1 on PPC (ORNL summit) and it does allow linking of shared 
objects with xlf via the same "-qmkshrobj" command line option used by 
xlc and xlC on lines 5208-5210 of m4/libtool.m4.

To make matters worse, the workaround of using $LD to link shared 
libraries with Fortran objects does not easily work when linking mixed 
language object code into such a shared library (one needs to know IBM 
XL paths to libraries like libibmc++.so and libstdc++.so, for example).  
This is easily resolved when one links with `xlf -qmkshrobj ...`.

It is suggested that this workaround check for compiler version or be 
deprecated.

Resolution is appreciated,


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    Bill Jones                                       W.T.JONES@NASA.GOV
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