Replace the runtime-sized stack array in the spectrum processing path
with std::vector to avoid compiler VLA extensions.
Although the spectrum template is not instantiated as part of the
current SDRangel build, GCC still emits -Wvla warnings while parsing
the template definition. This change removes those warnings and keeps
the template valid for future use.
Use std::copy() and vector::data() when accessing the underlying
storage.
Part of #2830
Signed-off-by: Robin Getz <rgetz503@gmail.com>
Robin Getz
fef5c27425