app-emulation/wine-staging: filter -mfunction-return=thunk for mingw

Unfortunately mingw doesn't play well with many security/mitigation
flags. May need to consider a mingw.eclass if keep adding more of
these to every ebuilds using it.

Bug: https://bugs.gentoo.org/878849
Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

app-emulation/wine-staging/wine-staging-7.17.ebuild

@@ -280,6 +280,7 @@ src_configure() {
 			: "${CROSSCFLAGS:=$(
 				filter-flags '-fstack-clash-protection' #758914
 				filter-flags '-fstack-protector*' #870136
+				filter-flags '-mfunction-return=thunk*' #878849
 				CC=${CROSSCC} test-flags-CC ${CFLAGS:--O2})}"
 			: "${CROSSLDFLAGS:=$(
 				filter-flags '-fuse-ld=*'

app-emulation/wine-staging/wine-staging-7.18.ebuild

@@ -280,6 +280,7 @@ src_configure() {
 			: "${CROSSCFLAGS:=$(
 				filter-flags '-fstack-clash-protection' #758914
 				filter-flags '-fstack-protector*' #870136
+				filter-flags '-mfunction-return=thunk*' #878849
 				CC=${CROSSCC} test-flags-CC ${CFLAGS:--O2})}"
 			: "${CROSSLDFLAGS:=$(
 				filter-flags '-fuse-ld=*'

app-emulation/wine-staging/wine-staging-7.19.ebuild

@@ -278,6 +278,7 @@ src_configure() {
 			: "${CROSSCFLAGS:=$(
 				filter-flags '-fstack-clash-protection' #758914
 				filter-flags '-fstack-protector*' #870136
+				filter-flags '-mfunction-return=thunk*' #878849
 				CC=${CROSSCC} test-flags-CC ${CFLAGS:--O2})}"
 			: "${CROSSLDFLAGS:=$(
 				filter-flags '-fuse-ld=*'

app-emulation/wine-staging/wine-staging-9999.ebuild

@@ -278,6 +278,7 @@ src_configure() {
 			: "${CROSSCFLAGS:=$(
 				filter-flags '-fstack-clash-protection' #758914
 				filter-flags '-fstack-protector*' #870136
+				filter-flags '-mfunction-return=thunk*' #878849
 				CC=${CROSSCC} test-flags-CC ${CFLAGS:--O2})}"
 			: "${CROSSLDFLAGS:=$(
 				filter-flags '-fuse-ld=*'