system/twin: Fix 15.0 build.

Signed-off-by: B. Watson <yalhcru@gmail.com>

Signed-off-by: Willy Sudiarto Raharjo <willysr@slackbuilds.org>

system/twin/twin.SlackBuild

@@ -23,6 +23,7 @@
 # ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # Slightly modified by Robby Workman <rworkman@slackbuilds.org>
+# 20220209 bkw: ...and fixed for 15.0 by B. Watson.
 
 cd $(dirname $0) ; CWD=$(pwd)
 
@@ -34,15 +35,12 @@ PKGTYPE=${PKGTYPE:-tgz}
 
 if [ -z "$ARCH" ]; then
   case "$( uname -m )" in
-    i?86) ARCH=i486 ;;
+    i?86) ARCH=i586 ;;
     arm*) ARCH=arm ;;
        *) ARCH=$( uname -m ) ;;
   esac
 fi
 
-# If the variable PRINT_PACKAGE_NAME is set, then this script will report what
-# the name of the created package would be, and then exit. This information
-# could be useful to other scripts.
 if [ ! -z "${PRINT_PACKAGE_NAME}" ]; then
   echo "$PRGNAM-$VERSION-$ARCH-$BUILD$TAG.$PKGTYPE"
   exit 0
@@ -52,8 +50,8 @@ TMP=${TMP:-/tmp/SBo}
 PKG=$TMP/package-$PRGNAM
 OUTPUT=${OUTPUT:-/tmp}
 
-if [ "$ARCH" = "i486" ]; then
-  SLKCFLAGS="-O2 -march=i486 -mtune=i686"
+if [ "$ARCH" = "i586" ]; then
+  SLKCFLAGS="-O2 -march=i586 -mtune=i686"
   LIBDIRSUFFIX=""
 elif [ "$ARCH" = "i686" ]; then
   SLKCFLAGS="-O2 -march=i686 -mtune=i686"
@@ -78,8 +76,9 @@ find -L . \
  \( -perm 666 -o -perm 664 -o -perm 640 -o -perm 600 -o -perm 444 \
  -o -perm 440 -o -perm 400 \) -exec chmod 644 {} \;
 
-CFLAGS="$SLKCFLAGS" \
-CXXFLAGS="$SLKCFLAGS" \
+SLKCFLAGS+=" -fcommon"
+
+# 20220209 bkw: configure ignores CFLAGS from environment.
 ./configure \
   --prefix=/usr \
   --libdir=/usr/lib${LIBDIRSUFFIX} \
@@ -88,7 +87,7 @@ CXXFLAGS="$SLKCFLAGS" \
   --mandir=/usr/man \
   --build=$ARCH-slackware-linux
 
-make -j1
+make -j1 CFLAGS="$SLKCFLAGS" CXXFLAGS="$SLKCFLAGS"
 make install DESTDIR=$PKG
 
 find $PKG | xargs file | grep -e "executable" -e "shared object" | grep ELF \