* Per #2272 and #1877, MinGW has issues when delay loading libraries, but
it is possible to apply a workaround to alleviate them, by redefining
DECLSPEC_IMPORT before including the corresponding headers.
* This is a bit more tricky to accomplish for virtdisk, as MinGW's windows.h
header does include virtdisk.h on its own (rather than expect a formal
include as MSVC does), so we have to prevent the virtdisk.h inclusion
first, by defining a macro, and then apply our workaround.
* Per https://sourceforge.net/p/mingw-w64/mailman/mingw-w64-public/thread/ea87573f-65ea-44a2-b4bb-ca96c0a136ab%40akeo.ie/#msg58793876
we are hoping that this should be a temporary workaround and that the root
cause of the issue will be fixed in binutils.
* Closes#2513.
* This reverts 3194a4dac4 on account that MinGW's delay loading of
wininet.dll causes the application to prematurely close.
* Yet another episode of the never ending #1877 saga...
* Now that we can delay-load DLLs for both MinGW and MSVC, we can remove the
cumbersome direct DLL hooks into wininet.dll (which is vulnerable to side
loading when not delay-loaded) and revert to using direct API calls instead.
* This reverts part of e1d864f755.
* Also attempt to silence a Coverity warning.
