Changed multi-line C comments into another style.

The left side doesn't look unbalanced.

src/common/abend.c

@@ -50,8 +50,8 @@
 
 void AbEnd (const char* Format, ...)
 /* Print a message preceeded by the program name and terminate the program
- * with an error exit code.
- */
+** with an error exit code.
+*/
 {
     va_list ap;