[lmi] [PATCH] Add missing <climits>

[Vadim Zeitlin]

 Hello,

 Building test_coding_rules with g++ 8 I was getting these errors:

---------------------------------- >8 --------------------------------------
main_common.hpp:30:20: error: ‘CHAR_BIT’ was not declared in this scope
 static_assert(8 == CHAR_BIT);
                    ^~~~~~~~
main_common.hpp:30:20: note: ‘CHAR_BIT’ is defined in header ‘<climits>’; did 
you forget to ‘#include <climits>’?
+#include <climits>

 static_assert(8 == CHAR_BIT);
                    ^~~~~~~~
---------------------------------- >8 --------------------------------------

so I've made a trivial patch fixing this as advised by gcc, please see

        https://github.com/vadz/lmi/pull/93

 Thanks in advance for applying it,
VZ