gdb: add patches from sabotage to make this build/work with musl.

srcpkgs/gdb/patches/gdb-76-linux-low-threaddb.patch

@@ -0,0 +1,32 @@
+this patch fixes compilation of gdbserver on systems that don't have
+thread_db.h. in that case we fall back to gdb's own copy 
+"gdb_thread_db.h", so the typedef of the td_thrhandle_t member is 
+available, which is accessed in other parts of the code without
+checking whether thread_db.h is available.
+this is by far the cleaner solution, removing the accesses to the
+th member in other parts of the source would either litter it with
+ifdefs or cripple the functionality.
+
+--- gdb-7.6.2.org/gdb/gdbserver/linux-low.h
++++ gdb-7.6.2/gdb/gdbserver/linux-low.h
+@@ -18,6 +18,8 @@
+ 
+ #ifdef HAVE_THREAD_DB_H
+ #include <thread_db.h>
++#else
++#include "gdb_thread_db.h"
+ #endif
+ #include <signal.h>
+ 
+@@ -270,11 +272,9 @@
+   int need_step_over;
+ 
+   int thread_known;
+-#ifdef HAVE_THREAD_DB_H
+   /* The thread handle, used for e.g. TLS access.  Only valid if
+      THREAD_KNOWN is set.  */
+   td_thrhandle_t th;
+-#endif
+ 
+   /* Arch-specific additions.  */
+   struct arch_lwp_info *arch_private;