move __abort_lock to its own file and drop pointless weak_alias trick

the dummy definition of __abort_lock in sigaction.c was performing
exactly the same role that putting the lock in its own source file
could and should have been used to achieve.

while we're moving it, give it a proper declaration.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/exit/abort_lock.c b/src/exit/abort_lock.c
new file mode 100644
index 00000000..3af72c7b
--- /dev/null
+++ b/src/exit/abort_lock.c
@@ -0,0 +1,3 @@
+#include "pthread_impl.h"
+
+volatile int __abort_lock[1];