vboxguestdrivers: Fix build failure due to the last update.

the utsrelease.h is not included in the STAGING_KERNEL_DIR, but in STAGING_KERNEL_BUILDDIR

So, adding a hacky symlink into the source directory fixes the issue for now.
This can be re-evaluated if poky maintainers start shipping such file into another directory or patch module*.bbclass to take account
of this additional dir into *FLAGS

https://errors.yoctoproject.org/Errors/Details/613563/

make: Entering directory 'TOPDIR/build/tmp/work/qemux86-yoe-linux/vboxguestdrivers/6.1.28-r0/vboxguestdrivers-6.1.28/utils'
i686-yoe-linux-gcc  -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -fstack-protector-strong  -O2 -D_FORTIFY_SOURCE=2 -Wformat -Wformat-security -Werror=format-security --sysroot=TOPDIR/build/tmp/work/qemux86-yoe-linux/vboxguestdrivers/6.1.28-r0/recipe-sysroot  -I. -I../vboxsf -I../vboxsf/include -DRT_OS_LINUX -DIN_RING0 -DIN_RT_R0 -DIN_SUP_R0 -DVBOX -DVBOX_WITH_HGCM -DIN_MODULE -DIN_GUEST_R0 -c -o mount.vboxsf.o mount.vboxsf.c
i686-yoe-linux-gcc  -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -fstack-protector-strong  -O2 -D_FORTIFY_SOURCE=2 -Wformat -Wformat-security -Werror=format-security --sysroot=TOPDIR/build/tmp/work/qemux86-yoe-linux/vboxguestdrivers/6.1.28-r0/recipe-sysroot  -I. -I../vboxsf -I../vboxsf/include -DRT_OS_LINUX -DIN_RING0 -DIN_RT_R0 -DIN_SUP_R0 -DVBOX -DVBOX_WITH_HGCM -DIN_MODULE -DIN_GUEST_R0 -c -o vbsfmount.o vbsfmount.c
In file included from ../vboxsf/include/iprt/stdarg.h:47,
                 from ../vboxsf/include/iprt/types.h:34,
                 from ../vboxsf/include/iprt/string.h:33,
                 from mount.vboxsf.c:53:
../vboxsf/include/iprt/linux/version.h:40:11: fatal error: generated/utsrelease.h: No such file or directory
   40 | # include <generated/utsrelease.h>
      |           ^~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
Makefile:39: recipe for target 'mount.vboxsf.o' failed

Signed-off-by: Khem Raj <raj.khem@gmail.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers/Makefile.utils b/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers/Makefile.utils
index 495601f08f..5982e2d08c 100644
--- a/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers/Makefile.utils
+++ b/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers/Makefile.utils
@@ -13,7 +13,7 @@
 INCLUDES = -I. -I../vboxsf -I../vboxsf/include
 MOD_DEFS = -DRT_OS_LINUX -DIN_RING0 -DIN_RT_R0 \
            -DIN_SUP_R0 -DVBOX -DVBOX_WITH_HGCM -DIN_MODULE -DIN_GUEST_R0
-CFLAGS   = ${INCLUDES} ${MOD_DEFS}
+CFLAGS   = ${INCLUDES} ${MOD_DEFS} ${EXTRA_CFLAGS}
 LDFLAGS  =
 
 SRCS     = mount.vboxsf.c \
diff --git a/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers_6.1.28.bb b/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers_6.1.28.bb
index c7e73b222e..0265e38f5f 100644
--- a/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers_6.1.28.bb
+++ b/meta-oe/recipes-support/vboxguestdrivers/vboxguestdrivers_6.1.28.bb
@@ -54,7 +54,7 @@ do_configure:prepend() {
 # compile and install mount utility
 do_compile() {
     oe_runmake all
-    oe_runmake 'LD=${CC}' 'LDFLAGS=${LDFLAGS}' -C ${S}/utils
+    oe_runmake 'LD=${CC}' 'EXTRA_CFLAGS=-I${STAGING_KERNEL_BUILDDIR}/include/' 'LDFLAGS=${LDFLAGS}' -C ${S}/utils
     if ! [ -e vboxguest.ko -a -e vboxsf.ko -a -e vboxvideo.ko ] ; then
         echo "ERROR: One of vbox*.ko modules wasn't built"
         exit 1