Added autoconf check for "inline". You can now use it, it will be
defined to (empty) for compilers that do not have it.

diff --git a/include/config.h.in b/include/config.h.in
index dc2a2e9..3a2d167 100644
--- a/include/config.h.in
+++ b/include/config.h.in
@@ -3,6 +3,9 @@
 /* Define to empty if the keyword does not work.  */
 #undef const
 
+/* Define as __inline if that's what the C compiler calls it.  */
+#undef inline
+
 /* Define to `unsigned' if <sys/types.h> doesn't define.  */
 #undef size_t