lldb does not support gnu debuglink for PE/COFF files on Windows

[alvinhochun]

First, compile something:

d:\temp>clang++ -Og -g test.cpp -o test1.exe

d:\temp>lldb -a x86_64 test1
(lldb) target create --arch=x86_64 "test1"
Current executable set to 'test1' (x86_64)
(lldb) l main
File: d:\temp\test.cpp
   1    #include <cstdio>
   2
   3    int main() {
[snip]
(lldb) q

Then split the debugging info to a separate file:

d:\temp>objcopy --only-keep-debug test1.exe test1.exe.debug

d:\temp>strip --strip-debug test1.exe

d:\temp>objcopy --add-gnu-debuglink="test1.exe.debug" test1.exe

Now lldb does not load the debug symbols:

d:\temp>lldb -a x86_64 test1
(lldb) target create --arch=x86_64 "test1"
Current executable set to 'test1' (x86_64)
(lldb) l main
error: Could not find function named: "main".
(lldb) q

gdb loads them fine:

d:\temp>D:\dev\toolchain\mingw\x86_64-11.2.0-release-posix-seh-rt_v9-rev1\bin\gdb.exe test1.exe
D:\dev\toolchain\mingw\x86_64-11.2.0-release-posix-seh-rt_v9-rev1\bin\gdborig.exe: warning: Couldn't determine a path for the index cache directory.
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Reading symbols from test1.exe...
Reading symbols from d:\temp\test1.exe.debug...
(gdb) l main
1       #include <cstdio>
2
3       int main() {
[snip]
(gdb) q

Using llvm-mingw-20211002-ucrt-x86_64 toolchain from https://github.com/mstorsjo/llvm-mingw/releases/tag/20211002

[llvmbot]

@llvm/issue-subscribers-lldb

[alvinhochun]

https://reviews.llvm.org/D126367