move rsyscall out of pthread_create module

this is something of a tradeoff, as now set*id() functions, rather
than pthread_create, are what pull in the code overhead for dealing
with linux's refusal to implement proper POSIX thread-vs-process
semantics. my motivations are:

1. it's cleaner this way, especially cleaner to optimize out the
rsyscall locking overhead from pthread_create when it's not needed.
2. it's expected that only a tiny number of core system programs will
ever use set*id() functions, whereas many programs may want to use
threads, and making thread overhead tiny is an incentive for "light"
programs to try threads.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/internal/libc.h b/src/internal/libc.h
index be88dc04..c0039e77 100644
--- a/src/internal/libc.h
+++ b/src/internal/libc.h
@@ -10,7 +10,6 @@ struct __libc {
 	void (*lock)(volatile int *);
 	void (*lockfile)(FILE *);
 	void (*fork_handler)(int);
-	int (*rsyscall)(int, long, long, long, long, long, long);
 	int (*atexit)(void (*)(void));
 	void (*fini)(void);
 	void (*ldso_fini)(void);
@@ -48,6 +47,8 @@ void __lockfile(FILE *);
 #define CANCELPT_INHIBIT CANCELPT(2)
 #define CANCELPT_RESUME CANCELPT(-2)
 
+int __rsyscall(int, long, long, long, long, long, long);
+
 extern char **__environ;
 #define environ __environ