Fixes for warnings related to -Wimplicit-int.

cde/programs/dtksh/ksh93/src/lib/lib0ast/C.probe

@@ -125,7 +125,7 @@ fi
 mkdir suffix
 cd suffix
 for src in $probe_src
-do	echo "main(){return 0;}" > ../test.$src
+do	echo "int main(){return 0;}" > ../test.$src
 	rm -f test*
 	if	$cc -c ../test.$src
 	then	set test.*
@@ -157,7 +157,7 @@ cd ..
 case $src in
 c)	;;
 *)	echo '// (
-main()
+int main()
 {
 	class { public: int i; } j;
 	j.i = 0;
@@ -217,7 +217,7 @@ do	shift
 done
 
 echo '#include <stdio.h>
-main(){printf("hello");return(0);}' > dynamic.$src
+int main(){printf("hello");return(0);}' > dynamic.$src
 if	$cc -c dynamic.$src
 then	eval set x $probe_so
 	while	:
@@ -297,7 +297,7 @@ then	eval set x $probe_so
 	fi
 fi
 
-echo 'main(){return(0);}' > hosted.$src
+echo 'int main(){return(0);}' > hosted.$src
 $cc -o hosted.$exe hosted.$src && ./hosted.$exe && hosted=1
 
 cp /bin/echo cpp