This commit gets pkgsCross.*.pdfgrep a bit farther. It still fails
with the error below; if anybody recognizes it I'd appreciate a hint.
```
pdfgrep-aarch64-unknown-linux-gnu> aarch64-unknown-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I.. -I/nix/store/9kzvsy9ybsy2zvivz62ia881q9djf734-poppler-glib-aarch64-unknown-linux-gnu-23.02.0-dev/include/poppler/cpp -I/nix/store/6ib0mcvv0ascsydhpja2a1kcnwvxqnfp-pcre-aarch64-unknown-linux-gnu-8.45-dev/include -I/nix/store/yyyy71mx8j85hh1xknfy2nqgw4ihfchr-libgcrypt-aarch64-unknown-linux-gnu-1.10.1-dev/include -I/nix/store/mqx4d57dva5y5kg91a9pnlipdc6bfcxc-libgpg-error-aarch64-unknown-linux-gnu-1.46-dev/include -g -O2 -c -o pdfgrep.o pdfgrep.cc
pdfgrep-aarch64-unknown-linux-gnu> In file included from /nix/store/cha4mfjki3pv42xnfsfrgppr3w1zmh27-aarch64-unknown-linux-gnu-stage-final-gcc-12.2.0/aarch64-unknown-linux-gnu/include/c++/12.2.0/stdlib.h:36,
pdfgrep-aarch64-unknown-linux-gnu> from pdfgrep.cc:24:
pdfgrep-aarch64-unknown-linux-gnu> /nix/store/cha4mfjki3pv42xnfsfrgppr3w1zmh27-aarch64-unknown-linux-gnu-stage-final-gcc-12.2.0/aarch64-unknown-linux-gnu/include/c++/12.2.0/cstdlib:151:11: error: 'malloc' has not been declared in '::'
pdfgrep-aarch64-unknown-linux-gnu> 151 | using ::malloc;
pdfgrep-aarch64-unknown-linux-gnu> | ^~~~~~
pdfgrep-aarch64-unknown-linux-gnu> /nix/store/cha4mfjki3pv42xnfsfrgppr3w1zmh27-aarch64-unknown-linux-gnu-stage-final-gcc-12.2.0/aarch64-unknown-linux-gnu/include/c++/12.2.0/cstdlib:164:11: error: 'realloc' has not been declared in '::'
pdfgrep-aarch64-unknown-linux-gnu> 164 | using ::realloc;
pdfgrep-aarch64-unknown-linux-gnu> | ^~~~~~~
pdfgrep-aarch64-unknown-linux-gnu> /nix/store/cha4mfjki3pv42xnfsfrgppr3w1zmh27-aarch64-unknown-linux-gnu-stage-final-gcc-12.2.0/aarch64-unknown-linux-gnu/include/c++/12.2.0/stdlib.h:65:12: error: 'malloc' has not been declared in 'std'
pdfgrep-aarch64-unknown-linux-gnu> 65 | using std::malloc;
pdfgrep-aarch64-unknown-linux-gnu> | ^~~~~~
pdfgrep-aarch64-unknown-linux-gnu> /nix/store/cha4mfjki3pv42xnfsfrgppr3w1zmh27-aarch64-unknown-linux-gnu-stage-final-gcc-12.2.0/aarch64-unknown-linux-gnu/include/c++/12.2.0/stdlib.h:73:12: error: 'realloc' has not been declared in 'std'
pdfgrep-aarch64-unknown-linux-gnu> 73 | using std::realloc;
pdfgrep-aarch64-unknown-linux-gnu> | ^~~~~~~
pdfgrep-aarch64-unknown-linux-gnu> make[2]: *** [Makefile:413: pdfgrep.o] Error 1
pdfgrep-aarch64-unknown-linux-gnu> make[2]: Leaving directory '/build/pdfgrep-2.1.2/src'
pdfgrep-aarch64-unknown-linux-gnu> make[1]: *** [Makefile:388: all-recursive] Error 1
pdfgrep-aarch64-unknown-linux-gnu> make[1]: Leaving directory '/build/pdfgrep-2.1.2'
pdfgrep-aarch64-unknown-linux-gnu> make: *** [Makefile:329: all] Error 2
```
Previously we relied on an environment variable POPPLER_DATADIR which
practically noone used and everyone was expected to set. This is a good
candidate for a feature option because noone really _noticed_ that this data is
not available. Disabled by default because of this and size of the data (22M).
In line with the Nixpkgs manual.
A mechanical change, done with this command:
find pkgs -name "*.nix" | \
while read f; do \
sed -e 's/description\s*=\s*"\([a-z]\)/description = "\u\1/' -i "$f"; \
done
I manually skipped some:
* Descriptions starting with an abbreviation, a user name or package name
* Frequently generated expressions (haskell-packages.nix)