Remove: rdtsc and TIC/TOC based on CPU ticks (#11856)

Use TIC/TOC based on std::chrono instead. This information is also
easier to compare with others, as although it depends on CPU, it
means a bit more if "yours takes 4ms and mine takes 10ms".

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Add: use of Intel Intrinsics & RDTSC on e2k (MCST Elbrus 2000) (#9575)

MCST e2k (Elbrus 2000) architecture has half native / half software support of most Intel/AMD SIMD
e.g. MMX/SSE/SSE2/SSE3/SSSE3/SSE4.1/SSE4.2/AES/AVX/AVX2 & 3DNow!/SSE4a/XOP/FMA4

E2K - this is VLIW/EPIC architecture, like Intel Itanium (IA-64) architecture.
Ref: https://en.wikipedia.org/wiki/Elbrus_2000

Co-authored-by: Alexander Troosh @troosh, Konstantin Ivlev @sse4 and Dmitry Shcherbakov @crypto-das

Fix: [Emscripten] using TIC/TOC on this platform is silly

Stop throwing a warning about this, as it is not likely we will
ever implement it.

Remove: DOS support

In 10 years there was no active development on DOS. Although it
turned out to still work, the FPS was very bad. There is little
interest in the current community to look into this.

Further more, we like to switch to c++11 functions for threads,
which are not implemented by DJGPP, the only current compiler
for DOS.

Additionally, DOS is the only platform which does not support
networking. It is the reason we have tons of #ifdefs to support
disabling networking.

By removing DOS support, we can both use c++11 functions for threads,
and remove all the code related to disabling network. Sadly, this
means we have to see DOS go.

Of course, if you feel up for the task, simply revert this commit,
and implement stub c++11 functions for threads and stub functions
for networking. We are more than happy to accept such Pull Request.