Avoid implicit int in inline keyword check.

This prevents the check from going wrong with future compilers which
do not support implicit ints.

Submitted upstream: <https://github.com/s-u/rJava/pull/305>

diff --git a/rJava/configure b/rJava/configure
index 4858bc30fa9610b3..41dd6c9fe27617c8 100755
--- a/rJava/configure
+++ b/rJava/configure
@@ -3624,7 +3624,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 static inline int foo(int a, int b);
-static f = 1;
+static int f = 1;
 static inline int foo(int a, int b) { return a+b; }
 int main(void) {
     return foo(f,-1);
diff --git a/rJava/configure.ac b/rJava/configure.ac
index 79a175f46be77cf7..14090b77b9fb22c5 100644
--- a/rJava/configure.ac
+++ b/rJava/configure.ac
@@ -104,7 +104,7 @@ AS_MESSAGE([checking whether ${CC} supports static inline...])
 can_inline=no
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
 static inline int foo(int a, int b);
-static f = 1;
+static int f = 1;
 static inline int foo(int a, int b) { return a+b; }
 int main(void) {
     return foo(f,-1);