musl: restore lock skipping for mostly-singlethreaded programs, and related patches

The remainder of the patch series proposed by upstream [2] for the locking
synchronization issue [1].

[1] https://www.openwall.com/lists/musl/2020/05/22/3
[2] https://www.openwall.com/lists/musl/2020/05/22/10

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

1 files changed, 25 insertions, 0 deletions

diff --git a/toolchain/musl/patches/500-0003-cut-down-size-of-some-libc-struct-members.patch b/toolchain/musl/patches/500-0003-cut-down-size-of-some-libc-struct-members.patch
new file mode 100644
index 0000000000..6650434397
--- /dev/null
+++ b/toolchain/musl/patches/500-0003-cut-down-size-of-some-libc-struct-members.patch
@@ -0,0 +1,25 @@
+From f12888e9eb9eed60cc266b899dcafecb4752964a Mon Sep 17 00:00:00 2001
+From: Rich Felker <dalias@aerifal.cx>
+Date: Fri, 22 May 2020 17:25:38 -0400
+Subject: [PATCH 3/4] cut down size of some libc struct members
+
+these are all flags that can be single-byte values.
+---
+ src/internal/libc.h | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+--- a/src/internal/libc.h
++++ b/src/internal/libc.h
+@@ -18,9 +18,9 @@ struct tls_module {
+ };
+ 
+ struct __libc {
+-	int can_do_threads;
+-	int threaded;
+-	int secure;
++	char can_do_threads;
++	char threaded;
++	char secure;
+ 	int threads_minus_1;
+ 	size_t *auxv;
+ 	struct tls_module *tls_head;