UBSAN runtime errors

[mattdowle]

Ran dev through full Rdevel-strict-clang CMD check added in #5509

$ find data.table.Rcheck -name "*.Rout" -exec grep -H "runtime error" {} \;
data.table.Rcheck/tests/nafill.Rout:assign.c:1006:21: runtime error: inf is outside the range of representable values of type 'int'
data.table.Rcheck/tests/nafill.Rout:assign.c:899:21: runtime error: -4.61169e+18 is outside the range of representable values of type 'int'
data.table.Rcheck/tests/nafill.Rout:assign.c:906:21: runtime error: -4.61169e+18 is outside the range of representable values of type 'int'
data.table.Rcheck/tests/nafill.Rout:assign.c:1023:21: runtime error: -1.84467e+19 is outside the range of representable values of type 'long'
data.table.Rcheck/tests/main.Rout:utils.c:8:38: runtime error: 2.14748e+09 is outside the range of representable values of type 'int'
data.table.Rcheck/tests/main.Rout:gsumm.c:1167:70: runtime error: nan is outside the range of representable values of type 'long'

I'll need to run again but using test.data.table() to get the test numbers ...

[mattdowle]

> test.data.table()
...
Running test id 2206.02          utils.c:8:38: runtime error: 2.14748e+09 is outside the range of representable values of type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior utils.c:8:38 in 
Running test id 2226.2          gsumm.c:1167:70: runtime error: nan is outside the range of representable values of type 'long'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior gsumm.c:1167:70 in 
...

> test.data.table("nafill.Rraw")
...
Running test id 1.08          assign.c:1006:21: runtime error: inf is outside the range of representable values of type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior assign.c:1006:21 in 
Running test id 6.47          assign.c:899:21: runtime error: -4.61169e+18 is outside the range of representable values of type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior assign.c:899:21 in 
assign.c:906:21: runtime error: -4.61169e+18 is outside the range of representable values of type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior assign.c:906:21 in 
Running test id 6.48          assign.c:1023:21: runtime error: -1.84467e+19 is outside the range of representable values of type 'long'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior assign.c:1023:21 in 
...