rpmcli.h forces a public dependency on popt includes

This is mildly annoying, librpm users don't need to link to popt but
this one include in rpmcli.h (that most API users wont even use) forces
a public dependency on it.

Another possibility could be splitting out the "cli" part of librpm
one way or another, but that doesn't seem worth all the trouble it would
be.

lib/CMakeLists.txt

@@ -18,6 +18,8 @@ target_include_directories(librpm PRIVATE
 	${CMAKE_CURRENT_BINARY_DIR}
 	${Intl_INCLUDE_DIRS}
 )
+# This is needed for rpmcli.h
+target_include_directories(librpm PUBLIC ${POPT_INCLUDE_DIRS})
 
 target_sources(librpm PRIVATE
 	backend/dbi.c backend/dbi.h backend/dummydb.c