libsigsegv: add Blackfin support

Fixes:

 http://autobuild.buildroot.org/results/5e2/5e2c627cfcb2699b16a82eb9554f2c9dfabd5483/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libsigsegv/libsigsegv-0004-fix-bfin-build.patch

@@ -0,0 +1,19 @@
+Add stack direction for Blackfin
+
+The stack grows downward on Blackfin, see
+https://sourceware.org/binutils/docs/as/Blackfin-Syntax.html: "The
+stack grows by decrementing the stack pointer.".
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Index: b/m4/stack-direction.m4
+===================================================================
+--- a/m4/stack-direction.m4
++++ b/m4/stack-direction.m4
+@@ -18,6 +18,7 @@
+       arc | \
+       arm* | strongarm* | xscale* | \
+       avr | avr32 | \
++      bfin | \
+       c1 | c2 | c32 | c34 | c38 | \
+       clipper | \
+       cris | \