libbpf-cargo: escape map names

commit 51ffd0f added support for custom sections.

this broke skeleton generation when bpf_printk() was used
along with BPF_NO_GLOBAL_DATA, as e.g. the map '.rodata.str1.1'
contains invalid chars. add simple escaping to the map name as
well (similar to the one used for the section name)

Signed-off-by: Eliad Peller <eliad.peller@wiz.io>

Author: eliad-wiz

libbpf-cargo/src/gen/mod.rs

@@ -366,7 +366,7 @@ fn gen_skel_map_defs(
 
         for map in MapIter::new(object.as_mut_ptr()) {
             let map_name = match get_map_name(map)? {
-                Some(n) => n,
+                Some(n) => n.replace('.', "_"),
                 None => continue,
             };