Add gcc intrinsics implementations for atomic and mutex
diff --git a/configure.ac b/configure.ac
index 44b0df4..edb8820 100644
--- a/configure.ac
+++ b/configure.ac
@@ -52,8 +52,8 @@
 dnl GTK_DOC_CHECK([1.15],[--flavour no-tmpl])
 
 # Functions and headers
-AC_CHECK_FUNCS(atexit mprotect sysconf getpagesize mmap _setmode isatty)
-AC_CHECK_HEADERS(unistd.h sys/mman.h io.h)
+AC_CHECK_FUNCS(atexit mprotect sysconf getpagesize sched_yield mmap _setmode isatty)
+AC_CHECK_HEADERS(unistd.h sys/mman.h sched.h io.h)
 
 # Compiler flags
 AC_CANONICAL_HOST