[PATCH v2] gprof: only process line numbers for intersection of vmas and histograms

[Richard Allen]

> Here is the patch to delay loading the symbol table until its first use.
> Does it work for you?

I changed core_create_line_syms() to call get_symtab_direct()
to fix runaway recursion and stack overflow.

I ran gprof with small gmon file against the Linux kernel debug symbols:

Before: 55 minutes.
After: ~8 seconds.

Also, I'm not sure if it is enough for core_create_line_syms() to check
only the histograms for symbols. Do you think we'll also need to lookup
symbols for basic-block and call-graph addresses?

-Richard