Add patch to enable SIGBUS capture

Kernels older than 3.18.6 emit SIGBUS signal upon stackoverflow instead of SIGSEGV. This patch enables the capture of SIGBUS (just as it is done on Darwin).

Applying it fixes https://github.com/NixOS/nixpkgs/issues/6028 and https://github.com/NixOS/nixpkgs/issues/28464#issuecomment-324255704

pkgs/development/libraries/libsigsegv/sigbus_fix.patch

@@ -0,0 +1,8 @@
+--- a/src/signals.h	2017-08-23 14:07:05.000000000 +0100
++++ b/src/signals.h	2017-08-23 14:06:53.000000000 +0100
+@@ -18,4 +18,4 @@
+ /* List of signals that are sent when an invalid virtual memory address
+    is accessed, or when the stack overflows.  */
+ #define SIGSEGV_FOR_ALL_SIGNALS(var,body) \
+-  { int var; var = SIGSEGV; { body } }
++  { int var; var = SIGSEGV; { body } var = SIGBUS; { body } }