app-emulation/open-vmdk: fix build issues with gcc 10

As gcc 10 or newer defaults to `-fno-common`, we need to define only
once in a *.c file, instead of *.h that can be imported multiple times
by *.c files.

See also https://github.com/vmware/open-vmdk/pull/13.

sdk_container/src/third_party/coreos-overlay/app-emulation/open-vmdk/files/vmdk-fix-build-issues-with-gcc-10-or-newer.patch

@@ -0,0 +1,51 @@
+From 74dffbca5d6fa37ed4ecd9b3a75206e33497e3df Mon Sep 17 00:00:00 2001
+Message-Id: <74dffbca5d6fa37ed4ecd9b3a75206e33497e3df.1644245904.git.dpark@linux.microsoft.com>
+From: Dongsu Park <dpark@linux.microsoft.com>
+Date: Mon, 7 Feb 2022 15:44:24 +0100
+Subject: [PATCH] vmdk: fix build issues with gcc 10 or newer
+
+As gcc 10 or newer defaults to `-fno-common`, we need to define only
+once in a *.c file, instead of *.h that can be imported multiple times
+by *.c files.
+
+Otherwise, build would fail like:
+```
+.../x86_64-pc-linux-gnu/bin/ld:
+../build/vmdk/mkdisk.o:.../vmdk/diskinfo.h:38:
+multiple definition of `toolsVersion';
+../build/vmdk/flat.o:.../vmdk/diskinfo.h:38: first defined here
+```
+---
+ vmdk/diskinfo.h | 2 +-
+ vmdk/mkdisk.c   | 2 ++
+ 2 files changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/vmdk/diskinfo.h b/vmdk/diskinfo.h
+index 2b58f432..f4f94419 100644
+--- a/vmdk/diskinfo.h
++++ b/vmdk/diskinfo.h
+@@ -35,7 +35,7 @@ struct DiskInfo {
+ 	const DiskInfoVMT *vmt;
+ };
+ 
+-char *toolsVersion; /* toolsVersion in metadata */
++extern char *toolsVersion; /* toolsVersion in metadata */
+ 
+ DiskInfo *Flat_Open(const char *fileName);
+ DiskInfo *Flat_Create(const char *fileName, off_t capacity);
+diff --git a/vmdk/mkdisk.c b/vmdk/mkdisk.c
+index b6c0cc94..b66b7d5d 100644
+--- a/vmdk/mkdisk.c
++++ b/vmdk/mkdisk.c
+@@ -24,6 +24,8 @@
+ #include <string.h>
+ #include <getopt.h>
+ 
++char *toolsVersion; /* toolsVersion in metadata */
++
+ static int
+ copyData(DiskInfo *dst,
+          off_t dstOffset,
+-- 
+2.34.1
+

sdk_container/src/third_party/coreos-overlay/app-emulation/open-vmdk/open-vmdk-1.0.ebuild

@@ -21,6 +21,10 @@ IUSE=""
 DEPEND=""
 RDEPEND="${DEPEND}"
 
+PATCHES=(
+	"${FILESDIR}/vmdk-fix-build-issues-with-gcc-10-or-newer.patch"
+)
+
 src_install() {
 	emake DESTDIR="${D}" install
 }