GNU -Wall Warning Reduction

[scrasmussen]

Reducing GNU -Wall warnings per issue #495.

Commits fix the following warning flags implied in -Wall

Compiler Flag	Description
-Wampersand	Warn about missing ampersand in continued character constants
-Wtabs	By default, tabs are accepted as whitespace, but tabs are not members of the Fortran Character Set.
-Wline-truncation	Warn when a source code line will be truncated
-Wcharacter-truncation	Warn when a character assignment will truncate the assigned string
-Wreturn-type	Warn when return value is not set

[SamuelTrahanNOAA]

All good changes. A note on this one. Perhaps the GNU compiler is not up-to-date, but:

Warn when a source code line will be truncated

The line length limit in Fortran 2023 is ten thousand characters (10,000 characters). For continued lines (using &) the limit is one million characters (1,000,000 characters). In other words, there's probably nowhere in the UFS code that passes the Fortran line length limits. Only the most complicated cpp-generated code risks hitting the line length limits. Alas, we are not using 2030s-era compilers, so we are stuck with the Fortran 2018 limits.

[grantfirl]

This should also be targeted at ufs-community:ufs/dev