debuginfod: Support queries for ELF/DWARF sections
Add new function debuginfod_find_section which queries debuginfod
servers for the raw binary contents of the specified ELF/DWARF section
in a file matching the given build-id.
Extend the server webapi to support section queries. Section query
URLS have the following format: /buildid/BUILDID/section/SECTION
The server will attempt to extract the section from a debuginfo file
matching the given build-id. If the debuginfo file cannot be found
or the section has type SHT_NOBITS, the server will attempt to extract
the section from the executable file matching the build-id.
If the server is built without section query support, the client will
attempt to download the debuginfo matching the build-id and extract the
section. If the debuginfo file cannot be found or the section has type
SHT_NOBITS, the server will attempt to download the executable file
matching the build-id and extract the section.