libtest/make: generate lib1521.c

[bagder]

... instead of having the generated code checked in. This saves space in
the tarball but primarily automatically adapts to newly added options.

[coveralls]

Coverage decreased (-0.004%) to 73.807% when pulling 8f06243 on bagder/generate-lib1521 into 922f800 on master.

[coveralls]

Coverage increased (+0.03%) to 73.839% when pulling 8f06243 on bagder/generate-lib1521 into 922f800 on master.

[jay]

I tried this in mingw and it works ok (with and without a pre-existing lib1521). Note lib1521.c isn't removed in your changes. Also it's failing one of the CI configs with weirdness

make[2]: *** No rule to make target `mk-lib1521.pl', needed by `lib1521.c'. Stop.
make[2]: Leaving directory `/home/travis/build/curl/curl/build/tests/libtest'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/travis/build/curl/curl/build/tests'
make: *** [test] Error 2

[bagder]

Right thanks, needs some polishing...

[coveralls]

Coverage increased (+0.008%) to 73.819% when pulling 8909be7 on bagder/generate-lib1521 into 922f800 on master.

[bagder]

right, the cmake system needs a poke too...

[coveralls]

Coverage increased (+0.02%) to 73.827% when pulling 042454f on bagder/generate-lib1521 into 922f800 on master.

[coveralls]

Coverage increased (+0.04%) to 73.851% when pulling e09ec2e on bagder/generate-lib1521 into 922f800 on master.

[dfandrich]

This seems to have broken all the autobuilds, presumably when built out of tree.

[bagder]

Gah, how did I miss that? =(

[dfandrich]

My fix is in PR#1628