qemu: remove outdated musl patch.

They stopped using these constants with [1].

[1] b1d2e476e9

srcpkgs/qemu/patches/musl-F_SHLCK-and-F_EXLCK.patch

@@ -1,19 +0,0 @@
-This patch was not upstreamed to qemu as those should probably be
-defined in musl libc.
-
---- linux-user/syscall.c.orig	2016-12-21 15:42:53.453155713 +0100
-+++ linux-user/syscall.c	2016-12-21 15:43:34.995638423 +0100
-@@ -114,6 +114,13 @@
- 
- #include "qemu.h"
- 
-+#ifndef F_SHLCK
-+#define F_SHLCK 8
-+#endif
-+#ifndef F_EXLCK
-+#define F_EXLCK 4
-+#endif
-+
- #ifndef CLONE_IO
- #define CLONE_IO                0x80000000      /* Clone io context */
- #endif