Support DLL builds + Fix C RTL variants

Support DLL builds + Fix C RTL variants

We need to generate a import library without the version in the
filename. MSVC's `link.exe` accommodates this with the [`/implib:`
option][1], while C++Builder needs a separate run of [`implib.exe`][2].
Also fix the variants of the [C runtime library and startup objects][3].

[1]: https://docs.microsoft.com/en-us/cpp/build/reference/implib-name-import-library?view=msvc-160
[2]: http://docwiki.embarcadero.com/RADStudio/Sydney/en/IMPLIB.EXE,_the_Import_Library_Tool_for_Win32
[3]: http://docwiki.embarcadero.com/RADStudio/Sydney/en/Static_Runtime_Libraries

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/13540)