Implicit function declarations are errors on darwin/arm64.  This patch adds a missing include to one of the AC_TRY_RUNs in tcl.m4:


--- a/tcl.m4
+++ b/tcl.m4
@@ -2584,6 +2584,7 @@ AC_DEFUN([TEA_BUGGY_STRTOD], [
     if test "$tcl_strtod" = 1; then
 	AC_CACHE_CHECK([for Solaris2.4/Tru64 strtod bugs], tcl_cv_strtod_buggy,[
 	    AC_TRY_RUN([
+		#include <stdlib.h>
 		extern double strtod();
 		int main() {
 		    char *infString="Inf", *nanString="NaN", *spaceString=" ";