Fix AIX build bustage.

Not part of default build.

other-licenses/libart_lgpl/art_misc.h

@@ -23,8 +23,8 @@
 #ifndef __ART_MISC_H__
 #define __ART_MISC_H__
 
-#include <stdlib.h> /* for malloc, etc. */
-
+#include <stdlib.h> /* for malloc, etc.  */
+#include <math.h>   /* for M_PI, M_SQRT2 */ 
 /* The art_config.h file is automatically generated by
    gen_art_config.c and contains definitions of
    ART_SIZEOF_{CHAR,SHORT,INT,LONG} and art_u{8,16,32}. */