fileattrs: Add attr for pythondistdeps

Rather than having the pythondistdeps dependency generator run on
all Python code, this separate attr will activate it only if the
package includes Python dist metadata (such as egg-info or dist-info
for Python Eggs and Python Wheels, respectively).

This is much more efficient, too, since the generator is only run
in circumstances where it will provide useful information.

This is based on the dependency generator attr used in Mageia,
OpenMandriva, and other systems that use the generator.

fileattrs/Makefile.am

@@ -7,7 +7,7 @@ fattrsdir = $(rpmconfigdir)/fileattrs
 
 fattrs_DATA = \
 	debuginfo.attr desktop.attr elf.attr font.attr libtool.attr metainfo.attr \
-	perl.attr perllib.attr pkgconfig.attr python.attr ocaml.attr script.attr \
-	mono.attr
+	perl.attr perllib.attr pkgconfig.attr python.attr pythondist.attr ocaml.attr \
+	script.attr mono.attr
 
 EXTRA_DIST = $(fattrs_DATA)

fileattrs/pythondist.attr

@@ -0,0 +1,3 @@
+%__pythondist_provides	%{_rpmconfigdir}/pythondistdeps.py --provides --majorver-provides
+%__pythondist_requires	%{_rpmconfigdir}/pythondistdeps.py --requires
+%__pythondist_path		/lib(64)?/python[[:digit:]]\\.[[:digit:]]/.*\\.(dist.*|egg.*)$