development/portaudio: Fix builds with jack/jack2.

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

development/portaudio/portaudio.SlackBuild

@@ -73,6 +73,11 @@ 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 {} \;
 
+# 20200117 bkw: If jack (either v1 or v2) is installed, parallel builds
+# of portaudio fail. Could just hardcode -j1 in make command, but let's not
+# penalize those who aren't affected by it.
+pkg-config --exists jack && JFLAG=-j1
+
 CFLAGS="$SLKCFLAGS" \
 CXXFLAGS="$SLKCFLAGS" \
 ./configure \
@@ -84,7 +89,7 @@ CXXFLAGS="$SLKCFLAGS" \
   --enable-cxx \
   --build=$ARCH-slackware-linux
 
-make
+make $JFLAG
 make install DESTDIR=$PKG
 
 find $PKG -print0 | xargs -0 file | grep -e "executable" -e "shared object" | grep ELF \