Remove symtab links from dwarf2_psymtab and dwarf2_per_cu_quick_data
The dwarf2_psymtab and dwarf2_per_cu_quick_data types contain a pointer
to a compunit_symtab, which is a pointer to the corresponding full
symtab. The dwarf2_psymtab and dwarf2_per_cu_quick_data objects are
going to become objfile-independent, and possibly shared by multiple
objfiles, whereas compunit_symtab will stay objfile-dependent. This
backlink to the compunit_symtab must therefore be removed.
This patch replaces them with a vector in the dwarf2_per_objfile type,
that serves as a mapping from dwarf2_per_cu_data objects to
compunit_symtab objects, for this particular objfile. The vector is
indexed using the index assigned to the dwarf2_per_cu_data at its
creation.
I removed the get_compunit_symtab, as it appears to bring not much value
over calling dwarf2_per_objfile::get_symtab directly.
gdb/ChangeLog:
YYYY-MM-DD Tom Tromey <tom@tromey.com>
YYYY-MM-DD Simon Marchi <simon.marchi@efficios.com>