gnu: gdb-9.2: Fix build with GCC 10 on powerpc64le-linux.

* gnu/packages/patches/gdb-9.2-sim-ppc-fno-common.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/gdb.scm (gdb-9.2)[source]: Use it.

gnu/local.mk

@@ -1095,6 +1095,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gcc-9-asan-fix-limits-include.patch	\
   %D%/packages/patches/gcc-9-strmov-store-file-names.patch	\
   %D%/packages/patches/gdb-hurd.patch				\
+  %D%/packages/patches/gdb-9.2-sim-ppc-fno-common.patch		\
   %D%/packages/patches/gd-fix-tests-on-i686.patch		\
   %D%/packages/patches/gd-brect-bounds.patch			\
   %D%/packages/patches/gd-Revert-fix-303-gdlib.pc-use-Requires-instead-of-Libs.patch	\

gnu/packages/gdb.scm

@@ -145,6 +145,7 @@ written in C, C++, Ada, Objective-C, Pascal and more.")
               (method url-fetch)
               (uri (string-append "mirror://gnu/gdb/gdb-"
                                   version ".tar.xz"))
+              (patches (search-patches "gdb-9.2-sim-ppc-fno-common.patch"))
               (sha256
                (base32
                 "0mf5fn8v937qwnal4ykn3ji1y2sxk0fa1yfqi679hxmpg6pdf31n"))))

gnu/packages/patches/gdb-9.2-sim-ppc-fno-common.patch

@@ -0,0 +1,123 @@
+From a2d12a56679db64d96e02a65933b2911f14c52a2 Mon Sep 17 00:00:00 2001
+From: Sebastian Huber <sebastian.huber@embedded-brains.de>
+Date: Wed, 1 Jul 2020 19:29:55 +0200
+Subject: [PATCH] sim/ppc: Fix linker error with -fno-common
+
+GCC 10 enables -fno-common by default.  This resulted in a multiple
+definition linker error since global variables were declared and defined
+in a header file:
+
+  ld: ld-insn.o:sim/ppc/ld-insn.h:221: multiple definition of
+  `max_model_fields_len'; igen.o:sim/ppc/ld-insn.h:221: first defined here
+
+sim/ppc
+
+	* ld-insn.h (last_model, last_model_data, last_model_function,
+	last_model_internal, last_model_macro, last_model_static):
+	Delete.
+	(max_model_fields_len, model_data, model_functions,
+	model_internal, model_macros, model_static, models): Declare, but do not
+	define.
+	* ld-insn.c (last_model, last_model_data, last_model_function,
+	last_model_internal, last_model_macro, last_model_static,
+	max_model_fields_len, model_data, model_functions,
+	model_internal, model_macros, model_static, models): Define.
+
+(cherry picked from commit ad8464f799a4c96c7ab8bdfec3f95846cf54f9b0)
+---
+
+This patch is a trivial backport from the upstream commit mentioned above.
+Only the ChangeLog had to be adapted.
+
+ sim/ppc/ChangeLog | 13 +++++++++++++
+ sim/ppc/ld-insn.c | 18 ++++++++++++++++++
+ sim/ppc/ld-insn.h | 24 +++++++-----------------
+ 3 files changed, 38 insertions(+), 17 deletions(-)
+
+diff --git a/sim/ppc/ChangeLog b/sim/ppc/ChangeLog
+index 665c7606d9eb..8f7150cee6b9 100644
+--- a/sim/ppc/ChangeLog
++++ b/sim/ppc/ChangeLog
+@@ -1,3 +1,16 @@
++2020-07-03  Sebastian Huber  <sebastian.huber@embedded-brains.de>
++
++	* ld-insn.h (last_model, last_model_data, last_model_function,
++	last_model_internal, last_model_macro, last_model_static):
++	Delete.
++	(max_model_fields_len, model_data, model_functions,
++	model_internal, model_macros, model_static, models): Declare, but do not
++	define.
++	* ld-insn.c (last_model, last_model_data, last_model_function,
++	last_model_internal, last_model_macro, last_model_static,
++	max_model_fields_len, model_data, model_functions,
++	model_internal, model_macros, model_static, models): Define.
++
+ 2019-01-26  Tom Tromey  <tom@tromey.com>
+ 
+ 	* Makefile.in (version.c): Use sim's create-version.sh.
+diff --git a/sim/ppc/ld-insn.c b/sim/ppc/ld-insn.c
+index e39131ca1334..585071a861ff 100644
+--- a/sim/ppc/ld-insn.c
++++ b/sim/ppc/ld-insn.c
+@@ -28,6 +28,24 @@
+ 
+ #include "igen.h"
+ 
++static model *last_model;
++
++static insn *last_model_macro;
++static insn *last_model_function;
++static insn *last_model_internal;
++static insn *last_model_static;
++static insn *last_model_data;
++
++model *models;
++
++insn *model_macros;
++insn *model_functions;
++insn *model_internal;
++insn *model_static;
++insn *model_data;
++
++int max_model_fields_len;
++
+ static void
+ update_depth(insn_table *entry,
+ 	     lf *file,
+diff --git a/sim/ppc/ld-insn.h b/sim/ppc/ld-insn.h
+index 88318ffa2b34..52baeaa2d846 100644
+--- a/sim/ppc/ld-insn.h
++++ b/sim/ppc/ld-insn.h
+@@ -200,25 +200,15 @@ extern insn_table *load_insn_table
+  table_include *includes,
+  cache_table **cache_rules);
+ 
+-model *models;
+-model *last_model;
++extern model *models;
+ 
+-insn *model_macros;
+-insn *last_model_macro;
++extern insn *model_macros;
++extern insn *model_functions;
++extern insn *model_internal;
++extern insn *model_static;
++extern insn *model_data;
+ 
+-insn *model_functions;
+-insn *last_model_function;
+-
+-insn *model_internal;
+-insn *last_model_internal;
+-
+-insn *model_static;
+-insn *last_model_static;
+-
+-insn *model_data;
+-insn *last_model_data;
+-
+-int max_model_fields_len;
++extern int max_model_fields_len;
+ 
+ extern void insn_table_insert_insn
+ (insn_table *table,