Resolve binary symlinks before finding its separate .debug file

Resolve binary symlinks before finding its separate .debug file

I have found LLDB cannot find separate debug info of Fedora /usr/bin/gdb.
It is because:

lrwxrwxrwx 1 root root       14 Jan 25 20:41 /usr/bin/gdb -> ../libexec/gdb*
-rwxr-xr-x 1 root root 10180296 Jan 25 20:41 /usr/libexec/gdb*
ls: cannot access '/usr/lib/debug/usr/bin/gdb-8.0.1-35.fc27.x86_64.debug': No such file or directory
-r--r--r-- 1 root root 29200464 Jan 25 20:41 /usr/lib/debug/usr/libexec/gdb-8.0.1-35.fc27.x86_64.debug

FYI that -8.0.1-35.fc27.x86_64.debug may look confusing, it was always just
.debug before.
Why is /usr/bin/gdb a symlink is offtopic for this bugreport, Fedora has it so
for some reasons.

It is always safest to look at the .debug file only after resolving all
symlinks on the binary file.

Differential revision: https://reviews.llvm.org/D42853

llvm-svn: 324224