Make epoll the default on Linux for event loop implementations.

meson.build

@@ -72,7 +72,7 @@ conf.set('JANET_NO_UMASK', not get_option('umask'))
 conf.set('JANET_NO_REALPATH', not get_option('realpath'))
 conf.set('JANET_NO_PROCESSES', not get_option('processes'))
 conf.set('JANET_SIMPLE_GETLINE', get_option('simple_getline'))
-conf.set('JANET_EV_EPOLL', get_option('epoll'))
+conf.set('JANET_EV_NO_EPOLL', not get_option('epoll'))
 conf.set('JANET_NO_THREADS', get_option('threads'))
 if get_option('os_name') != ''
   conf.set('JANET_OS_NAME', get_option('os_name'))

src/conf/janetconf.h

@@ -47,7 +47,7 @@
 /* #define JANET_STACK_MAX 16384 */
 /* #define JANET_OS_NAME my-custom-os */
 /* #define JANET_ARCH_NAME pdp-8 */
-/* #define JANET_EV_EPOLL */
+/* #define JANET_EV_NO_EPOLL */
 
 /* Custom vm allocator support */
 /* #include <mimalloc.h> */

src/include/janet.h

@@ -193,6 +193,11 @@ extern "C" {
 #define JANET_INT_TYPES
 #endif
 
+/* Enable or disable epoll on Linux */
+#if defined(JANET_LINUX) && !defined(JANET_EV_NO_EPOLL)
+#define JANET_EV_EPOLL
+#endif
+
 /* How to export symbols */
 #ifndef JANET_API
 #ifdef JANET_WINDOWS