gdb: fix compile error with GCC 6

Fixes #2387

repos/ports/ports/gdb.hash

@@ -1 +1 @@
-b3ce3adb094fd871ca90e7d6b51912bd8140d8d0
+79ebd0bd926cc0da0dee5cc0e9485a723d793e9d

repos/ports/src/noux-pkg/gdb/patches/gcc6.patch

@@ -0,0 +1,29 @@
+gcc6.patch
+
+ChangeLog part removed to make the patch apply on Genode.
+
+From 24b4cf66a626566e7903813a2e0156778f4903f9 Mon Sep 17 00:00:00 2001
+From: Szabolcs Nagy <szabolcs.nagy@arm.com>
+Date: Tue, 16 Jun 2015 13:35:33 +0100
+Subject: [PATCH] Fixes a compile time warnng about left shifting a negative
+ value.
+
+	* arm-dis.c (print_insn_coprocessor): Avoid negative shift.
+---
+ opcodes/ChangeLog | 4 ++++
+ opcodes/arm-dis.c | 2 +-
+ 2 files changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/opcodes/arm-dis.c b/opcodes/arm-dis.c
+index e9f4425..818847d 100644
+--- a/opcodes/arm-dis.c
++++ b/opcodes/arm-dis.c
+@@ -3352,7 +3352,7 @@ print_insn_coprocessor (bfd_vma pc,
+ 
+ 		    /* Is ``imm'' a negative number?  */
+ 		    if (imm & 0x40)
+-		      imm |= (-1 << 7);
++		      imm -= 0x80;
+ 
+ 		    func (stream, "%d", imm);
+ 		  }

repos/ports/src/noux-pkg/gdb/patches/series

@@ -5,3 +5,4 @@ x86_64.patch
 noux_build.patch
 gdbserver_genode.patch
 gdbserver_x86_64.patch
+gcc6.patch