[Qt] move SubstituteFonts() above ToolTipToRichTextFilter

- doesn't belong to the ToolTipToRichTextFilter class so move it up
Merge pull request #4659

c4bae53 [Qt] move SubstituteFonts() above ToolTipToRichTextFilter (Philip Kaufmann)
build: fix automake warnings about the use of INCLUDES

While we're at it, reduce the use of LIBS as well. This makes dependencies
explicit.

Fixes building with (the not-yet-merged) libsecp256k1 as well.

Github-Pull: #4689
Rebased-By: Wladimir J. van der laan <laanwj@gmail.com>
Rebased-From: 909b347 c0e5dda