Switches the module_mapper_t used by raw2trace to explicitly track individual segments, rather than collapsing them into the single whole-module mmap, in order to handle objects like vdso allocated in gaps between the segments.
Tested on a proprietary system where vdso was in the middle of ld.so, causing the opcode_mix tool to crash. (Creating a regression test would be complex, requiring synthesizing ELF files with the required characteristics.)
Fixes #4731 (closed)