Test value casts which are Undefined Behavior #793

Job	Run time
Linux centos 7	4m 12s
Linux fedora latest	4m 11s
Native Linux (WError)	5m 27s
Native Linux (libc++ debug)	5m 31s
Native Linux (c++17)	4m 45s
Cross mingw64 DLL	11m 9s
Cross mingw64 static	11m 11s
RTEMS5	14m 21s
Native Linux with clang	4m 30s
Native Linux with clang ubsan	4m 57s
Native Linux with libevent stable	4m 27s
Native Linux with 7.0.2	4m 44s
Native Linux with 3.15	3m 49s
Native Linux with 3.14	6m 5s
OSX	3m 56s
vs2019 DLL	7m 47s
vs2019 static	9m 37s
	1h 50m 39s

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