tools/thermal: tmon: use pkg-config to determine library dependencies

Some distros (e.g., Arch Linux) don't package the tinfo library
separately from ncurses, so don't unconditionally include it. Instead,
use pkg-config.

The $(STATIC) ugliness is to handle the reported build case from commit
6b533269

 ("tools/thermal: tmon: fix compilation errors when building
statically"), where a developer wants to be able to build with:

  make LDFLAGS=-static

which requires an additional pkg-config flag.

Finally, support a lowest common denominator fallback (-lpanel
-lncurses) for build systems that don't have pkg-config entries for
ncurses.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>