Fix 32085 Source file not recognized for gcc 11.4.0-compiled code

gprofng cannot read compressed section.
In the next release we plan to use libbfd everywhere instead of our ELF reader.
But in this release I use bfd_get_full_section_contents() only
when bfd_is_section_compressed() returns true.

gprofng/ChangeLog
2025-01-06  Vladimir Mezentsev  <vladimir.mezentsev@oracle.com>

	PR gprofng/32085
	* src/Elf.cc: Use bfd_get_full_section_contents to decompress a section.
	* src/Elf.h: Define SEC_DECOMPRESSED.