libsysprof: add utility to build symbol maps

These are useful to allow us to append symbol informatio to a capture file
using the existing symbol resolvers.

It can read/write a small format embedded within capture files so that
we can append them from the target machine rather than decoding from the
machine we run Sysprof UI on.

src/libsysprof/meson.build

@@ -53,6 +53,7 @@ libsysprof_private_sources = [
   'sysprof-kallsyms.c',
   'sysprof-line-reader.c',
   'sysprof-map-lookaside.c',
+  'sysprof-symbol-map.c',
   ipc_service_src,
   stackstash_sources,
   helpers_sources,