Packages: use the official RPM public API

instead of diving into its implementation detail to count installed rpm packages, which support CentOS

src/data/config.txt

@@ -165,4 +165,4 @@
 #--lib-DConf /usr/lib/libdconf.so
 #--lib-wayland /usr/lib/libwayland-client.so
 #--lib-XFConf /usr/lib/libxfconf-0.so
-#--lib-SQLite /usr/lib/libsqlite3.so
+#--lib-rpm /usr/lib/librpm.so

src/data/help.txt

@@ -93,7 +93,7 @@ Library options: Set the path of a library to load
    --lib-DConf <path>
    --lib-wayland <path>
    --lib-XFConf <path>
-   --lib-SQLite <path>
+   --lib-RPM <path>
 
 Module specific options:
    --disk-folders <folders>:     A colon separated list of folder paths for the disk output. Default is "/:/home"