Add missing alt code to 1990/baruch

I did this a while back but somehow forgot to do a git add baruch.alt.c
so the alt code was only referenced in the README.md and Makefile. That
has now been corrected.

1990/baruch/.gitignore

@@ -1 +1,2 @@
 baruch
+baruch.alt

1990/baruch/baruch.alt.c

@@ -0,0 +1,6 @@
+int v,i,j,k,l,s,a[99];
+int main(void)
+{
+	for(scanf("%d",&s);*a-s;v=a[j*=v]-a[i],k=i<s,j+=(v=j<s&&(!k&&!!printf(2+"\n\n%c"-(!l<<!j)," #Q"[l^v?(l^j)&1:2])&&++l||a[i]<s&&v&&v-i+j&&v+i-j))&&!(l%=s),v||(i==j?a[i+=k]=0:++a[i])>=s*k&&++a[--i])
+		;puts("");
+}