Revert "Mention the fact that binutils can't use the generated import libraries"

This reverts commit 9367988be7.

binutils actually can handle the short import format just fine.
It only has got issues with base mingw import libraries that contain
symbol aliases (which in llvm-dlltool is implemented via weak
symbols, and linking to weak symbols differ a bit between lld and
binutils ld).

README.md

@@ -84,9 +84,6 @@ normal GCC/binutils based MinGW.
   Sanitizer requires using a PDB file for symbolizing the error location and
   backtraces.
 - The sanitizers are only supported on x86.
-- The import libraries that this toolchain produces are in the same COFF
-  short import format as MSVC produces; GNU binutils doesn't support
-  this format.
 
 Additionally, one may run into other minor differences between GCC and clang.