crt: tests: update t_powi

The `main` function had wrong signature.

Add t_powi to testcases/Makefile.am.

Signed-off-by: Kirill Makurin <maiddaisuki@outlook.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>

mingw-w64-crt/testcases/Makefile.am

diff --git a/mingw-w64-crt/testcases/Makefile.am b/mingw-w64-crt/testcases/Makefile.am
index a384637..037f4c0 100644
--- a/mingw-w64-crt/testcases/Makefile.am
+++ b/mingw-w64-crt/testcases/Makefile.am
@@ -56,6 +56,7 @@
   t_mbsrtowcs \
   t_nullptrexception \
   t_pow \
+  t_powi \
   t_printf \
   t_printf_g_width \
   t_readdir \

mingw-w64-crt/testcases/t_powi.c

diff --git a/mingw-w64-crt/testcases/t_powi.c b/mingw-w64-crt/testcases/t_powi.c
index f3f07ce..636da4f 100644
--- a/mingw-w64-crt/testcases/t_powi.c
+++ b/mingw-w64-crt/testcases/t_powi.c
@@ -1,7 +1,7 @@
 #include <math.h>
 #include <stdio.h>
 
-int main(int argc, void **argv)
+int main(int argc, char **argv)
 {
     int i;
     double x, x2, z = pow(10.0, 15);