improved ifinstalled and made noisereduce use it (#930)

* made noisereduce executable

* improved `ifinstalled` script

* made `noisereduce` use `ifinstalled` script

* quoting for quiet shellcheck

.local/bin/ifinstalled

@@ -6,6 +6,8 @@
 # various other scripts for clarity's sake.
 
 for x in "$@";do
-	pacman -Qq "$x" >/dev/null 2>&1 ||
-		{ notify-send "📦 $x" "must be installed for this function." && exit 1 ;}
+	notify() { notify-send "📦 $x" "must be installed for this function." && exit 1 ;}
+	which_out="$( /usr/bin/which "$x" >/dev/null 2>&1 )" && exit 0 #you might have compiled the prog, and not install the repo pkg...
+	pkgname="$(pacman -Qqo "$which_out"  >/dev/null 2>&1 )" #...thats why two variables.
+	pacman -Qq "$pkgname" >/dev/null 2>&1 || notify
 done