libsysprof-analyze: add basic symbol cache

This relies on begin/end range for the symbols to create something akin to
an interval tree, albeit with GSequence. If performance needs to be
addressed, can probably augment SysprofSymbol for an interval rbtree.

src/libsysprof-analyze/meson.build

@@ -29,6 +29,7 @@ libsysprof_analyze_private_sources = [
   'sysprof-mount-device.c',
   'sysprof-mount-namespace.c',
   'sysprof-strings.c',
+  'sysprof-symbol-cache.c',
 ]
 
 libsysprof_analyze_public_headers = [