checkbadSource: enforce proper style in makefiles

Run fprettify

use integer and real kinds from ISO_C_binding

The kinds in this module are guaranteed to be compatible with the
corresponding C types.
Requires to include the ISO_C_binding module in interfaces and

use integer and real kinds from ISO_C_binding

The kinds in this module are guaranteed to be compatible with the
corresponding C types.
Requires to include the ISO_C_binding module in interfaces and stray
functions

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polishing.

thanks to @Pribec for the suggestions

use array notation (=vectorize)

give intent = (in,out,inout) and mark as pure

regular do without line number

consistent indentation (2 spaces)