Changed multi-line C comments into another style.

The left side doesn't look unbalanced.

src/sp65/convert.h

@@ -57,10 +57,10 @@
 
 StrBuf* ConvertTo (const Bitmap* B, const Collection* A);
 /* Convert the bitmap B into some sort of other binary format. The output is
- * stored in a string buffer (which is actually a dynamic char array) and
- * returned. The actual output format is taken from the "format" attribute
- * in the attribute collection A.
- */
+** stored in a string buffer (which is actually a dynamic char array) and
+** returned. The actual output format is taken from the "format" attribute
+** in the attribute collection A.
+*/
 
 void ListConversionTargets (FILE* F);
 /* Output a list of conversion targets */