The primary improvement here is in logc_assets.h. The original
implementation was assembling the format string in runtime, while now it
is assembled fully in compile time.

The minor improvement is in valgrind tool handling. If invalid or
unknown tool is passed it now prints valgrind error instead of shell
expansion error.

The code is now formatted with clang-format and shell-format. This
includes code formatting as well as comments change. Now C style
comments are used preferably and C++ style is used only for comments
such as TODO.
The change here is also in the SPDX comment. On one side using C++ style
has advantage of reducing it by one line but advantage of C style is
that even a simple editors can pick it up and possibly hide it as a
single section (such as folds in the Vim).