All 1990 entries now compile!

My first 41st, 51st and 29th (all depending on the base) birthday
updates (possibly more will follow but this is not a certainty). All the
1990 entries now compile!

In one we used a patch from Yusuke Endoh (thank you Yusuke!) which we
credited him in the README and in another we used a tip from him (use
-ansi at the compiler line) to get the other to compile (again, thank
you Yusuke!). We fixed the others. In the case of 1990/tbr/tbr.c the
author had supplied a shorter version and we fixed that one too.

Added 1990/.gitignore which has the built files of 1990 so that after
doing `cd 1990 ; make all' running `git status .' will not show any
untracked files.

1990/.gitignore

@@ -0,0 +1,18 @@
+baruch/baruch
+cmills/cmills
+dds/dds
+dg/dg
+jaw/atob
+jaw/jaw
+jaw/zcat
+pjr/pjr
+scjones/scjones
+stig/o
+stig/o.c
+tbr/tbr
+theorem/fibonacci
+theorem/fibonacci.c
+theorem/sorter
+theorem/sorter.c
+theorem/theorem
+westley/westley