gdbm: add patch to fix link failure against gcc 10

This also makes appending "-fcommon" to CFLAGS obsolete and enables
native builds with a host gcc v10.

(From OE-Core rev: 7717b35265e6ef8ef71a4eca4074294dfcc2110c)

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/gdbm/files/gdbm-fix-link-failure-against-gcc-10.patch

@@ -0,0 +1,47 @@
+From f993697af81c37df9c55e0ebedeb1b8b880506ae Mon Sep 17 00:00:00 2001
+From: Richard Leitner <richard.leitner@skidata.com>
+Date: Tue, 5 May 2020 11:59:42 +0200
+Subject: [PATCH] gdbm: fix link failure against gcc-10
+
+Copied from gentoo's solution at https://bugs.gentoo.org/show_bug.cgi?id=705898
+Original patch by Sergei Trofimovich <slyfox@gentoo.org>
+
+Original description:
+
+Before the change on gcc-10 link failed as:
+```
+  CCLD     gdbmtool
+ld: ./libgdbmapp.a(parseopt.o):(.bss+0x8): multiple definition of `parseopt_program_args';
+  gdbmtool.o:(.data.rel.local+0x260): first defined here
+ld: ./libgdbmapp.a(parseopt.o):(.bss+0x10): multiple definition of `parseopt_program_doc';
+  gdbmtool.o:(.data.rel.local+0x268): first defined here
+```
+
+gcc-10 will change the default from -fcommon to fno-common:
+    https://gcc.gnu.org/PR85678.
+
+The fix is to avoid multiple definition and rely on
+declarations only.
+
+Upstream-Status: Pending
+Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
+---
+ src/parseopt.c | 2 --
+ 1 file changed, 2 deletions(-)
+
+diff --git a/src/parseopt.c b/src/parseopt.c
+index 268e080..a4c8576 100644
+--- a/src/parseopt.c
++++ b/src/parseopt.c
+@@ -255,8 +255,6 @@ print_option_descr (const char *descr, size_t lmargin, size_t rmargin)
+ }
+ 
+ char *parseopt_program_name;
+-char *parseopt_program_doc;
+-char *parseopt_program_args;
+ const char *program_bug_address = "<" PACKAGE_BUGREPORT ">";
+ void (*parseopt_help_hook) (FILE *stream);
+ 
+-- 
+2.26.2
+

meta/recipes-support/gdbm/gdbm_1.18.1.bb

@@ -8,6 +8,7 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=241da1b9fe42e642cbb2c24d5e0c4d24"
 SRC_URI = "${GNU_MIRROR}/gdbm/gdbm-${PV}.tar.gz \
            file://run-ptest \
            file://ptest.patch \
+           file://gdbm-fix-link-failure-against-gcc-10.patch \
           "
 
 SRC_URI[md5sum] = "988dc82182121c7570e0cb8b4fcd5415"
@@ -23,8 +24,6 @@ CACHED_CONFIGUREVARS += "ac_cv_lib_ndbm_main=no ac_cv_lib_dbm_main=no"
 
 BBCLASSEXTEND = "native nativesdk"
 
-CFLAGS += "-fcommon"
-
 do_install_append () {
     # Create a symlink to ndbm.h and gdbm.h in include/gdbm to let other packages to find
     # these headers