fix many internal links

Fixed a number of internal links that need to
go to the GitHub site.

Ran `make www` to perform the above.

1990/tbr/README.md

@@ -92,7 +92,7 @@ of the program which we include below:
     e(x){x<0?write(2,"?\n$ "-x/4,2),x+1||(exit(1),0):5;}
 ```
 
-and in the [alternate source](tbr.alt.c). It has the `exit()` returns `void` fix
+and in the [alternate source](%%REPO_URL%%/1990/tbr/tbr.alt.c). It has the `exit()` returns `void` fix
 as well as the `gets()` to `fgets()` fix applied to it to make it functionally
 equivalent like the authors intended.
 

1990/tbr/index.html

@@ -436,7 +436,7 @@ of the program which we include below:</p>
     0),e(open(*i,0)):5,t?dup2(t,1)D t):i[2]?9 D
     1),e(creat(i[2],438)):2,e(execvp(*u,u))):e(chdir(u[1])*2):6;}
     e(x){x&lt;0?write(2,&quot;?\n$ &quot;-x/4,2),x+1||(exit(1),0):5;}</code></pre>
-<p>and in the <a href="tbr.alt.c">alternate source</a>. It has the <code>exit()</code> returns <code>void</code> fix
+<p>and in the <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1990/tbr/tbr.alt.c">alternate source</a>. It has the <code>exit()</code> returns <code>void</code> fix
 as well as the <code>gets()</code> to <code>fgets()</code> fix applied to it to make it functionally
 equivalent like the authors intended.</p>
 <h3 id="alternate-build">Alternate build:</h3>