!4452 had config generation first before building the component list
to be used in the build. This proved to be detrimental when a new target
is added as config generation would consider configs from both targets.
Removes the need to know/guess the paths to these libraries. Once we are gcc 8 only, we
can remove -nostdlib and no additional arguments are needed for system libraries.
The catch is: any time IDF overrides a symbol in the toolchain sysroot, we need
an undefined linker marker to make sure this symbol is seen by linker.
