Patch to improve cupsdir detection

Hello

Since really a lot of time we are shipping in Gentoo attached patch to adapt cupsdir to our cups installations (that uses /usr/libexec/cups instead of /usr/lib) :

index d9a2425..a382e05 100644
@@ -122,7 +122,7 @@ EXTRA_DIST += tools/dfubabel.1 tools/avctrl.8
 
 
 if CUPS
-cupsdir = $(libdir)/cups/backend
+cupsdir = `cups-config --serverbin`/backend
 
 cups_PROGRAMS = cups/bluetooth
 

I send this to inform you about it and, if possible, get it upstreamed :-)

Thanks a lot

index d9a2425..a382e05 100644
@@ -122,7 +122,7 @@ EXTRA_DIST += tools/dfubabel.1 tools/avctrl.8
 
 
 if CUPS
-cupsdir = $(libdir)/cups/backend
+cupsdir = `cups-config --serverbin`/backend
 
 cups_PROGRAMS = cups/bluetooth
 

Given that the cups backend doesn't actually require the cups headers or development packages, you'd need to check for cups-config existing, and then use a nice default if not present.

This should be done in acinclude.m4, with a new macro, which will get added to the generated configure.

Cheers