Some log messages may exceed max length for character variables

[mnlevy1981]

There are several places in the code where we write something to the variable log_message prior to updating the MARBL log with a call like

write(log_message, "(2A)") trim(str1), trim(str2)

we should really ensure that len_trim(str1) + len_trim(str2) <= len(log_message) before making those calls. (We are currently getting bitten by this in one section of marbl_config_mod due to a PGI compiler bug that seems to be populating str2 with garbage instead of setting it to what we want; there are other places where this sort of check could also come in handy, though.)

[mnlevy1981]

#168 addressed the specific instance in marbl_config_mod that was causing issues with PGI 17.4, but the issue as a whole has not yet been addressed.