bug#40783: GNU FreeFont silent build failure

[Leo Famulari]

The GNU FreeFont package is still using system* instead of invoke in its
install phase, and this is failing silently:

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mkdir 
/gnu/store/1nfp73g3s15dhpqjrbfsihk7jrcbbl1p-font-gnu-freefont-20120503/share/doc/font-gnu-freefont-20120503
cp -a README AUTHORS CREDITS COPYING ChangeLog INSTALL  
/gnu/store/1nfp73g3s15dhpqjrbfsihk7jrcbbl1p-font-gnu-freefont-20120503/share/doc/font-gnu-freefont-20120503
cp -a notes/usage.txt 
/gnu/store/1nfp73g3s15dhpqjrbfsihk7jrcbbl1p-font-gnu-freefont-20120503/share/doc/font-gnu-freefont-20120503/USAGE
cp -a notes/troubleshooting.txt 
/gnu/store/1nfp73g3s15dhpqjrbfsihk7jrcbbl1p-font-gnu-freefont-20120503/share/doc/font-gnu-freefont-20120503/TROUBLESHOOTING
tar czvf freefont-ttf-20200422.tar.gz freefont-20200422/
tar: freefont-20200422: Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors
make: *** [Makefile:64: ttftar] Error 2
phase `install' succeeded after 0.2 seconds
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Notice that it is using the current date. It doesn't work to use the
Unix epoch or the version of the package: 20120503 (see attached).

We should figure out what this is trying to accomplish, fix it, and
switch to invoke.

The fonts are getting installed AFAICT.

0001-gnu-GNU-FreeFont-Add-otf-and-woff-font-formats.patch
Description: Text document

source-date-epoch-snippet
Description: Text document