firebird: gcc6 compatibility part 1

Change-Id: I4fbb131a629275626510d5311550e8bf8cdef6d5

external/firebird/UnpackedTarball_firebird.mk

@@ -18,6 +18,7 @@ $(eval $(call gb_UnpackedTarball_add_patches,firebird,\
 		external/firebird/firebird-Engine12.patch \
 		external/firebird/firebird-rpath.patch.0 \
 		external/firebird/firebird-cloop-compiler.patch.1 \
+		external/firebird/firebird-gcc6.patch.1 \
 ))
 
 ifeq ($(OS)-$(COM),WNT-MSC)

external/firebird/firebird-gcc6.patch.1

+commit 3618aa2171674babf79ef935aa049c40a3db1321
+Author: asfernandes <asfernandes@users.sourceforge.net>
+Date:   Sat Mar 5 03:39:36 2016 +0000
+
+    Make the generated code compatible with gcc 6 in C++-14 mode.
+
+diff --git a/src/gpre/c_cxx.cpp b/src/gpre/c_cxx.cpp
+index 2af96c6..2dcffd6 100644
+--- a/src/gpre/c_cxx.cpp
++++ b/src/gpre/c_cxx.cpp
+@@ -2820,7 +2820,7 @@ static void gen_request(const gpre_req* request)
+ 		printa(0, "static %sshort\n   isc_%dl = %d;",
+ 			   (request->req_flags & REQ_extend_dpb) ? "" : CONST_STR,
+ 			   request->req_ident, request->req_length);
+-		printa(0, "static %schar\n   isc_%d [] = {", CONST_STR, request->req_ident);
++		printa(0, "static %sunsigned char\n   isc_%d [] = {", CONST_STR, request->req_ident);
+ 
+ 		const TEXT* string_type = "blr";
+ 		if (gpreGlob.sw_raw)