chore: make it possible to specify COMMON_OPTIONS for non-Ninja builds a well

[adelton]

Looking at

edgetx/tools/build-companion.sh

Lines 23 to 31 in 0087e25

	QUIET_FLAGS=""
	if [[ "$CMAKE_GENERATOR" == "Ninja" ]]; then
	QUIET_FLAGS="-- --quiet"
	else
	# Assume Makefile generator for non-Ninja builds
	COMMON_OPTIONS="-DCMAKE_RULE_MESSAGES=OFF"
	fi
	COMMON_OPTIONS="${COMMON_OPTIONS} -DCMAKE_BUILD_TYPE=Release -DCMAKE_MESSAGE_LOG_LEVEL=WARNING -Wno-dev -DGVARS=YES -DHELI=YES -DLUA=YES"

, it is possible to specify COMMON_OPTIONS environment variable when invoking tools/build-companion.sh with Ninja generator but not with non-Ninja builds. Being able to specify additional cmake parameters would be helpful for alternative build setups.

For example, rpm builds prefer to have all sources packaged in the source rpm rather than fetching them during build time. With this change we could then do things like

COMMON_OPTIONS="-DFETCHCONTENT_SOURCE_DIR_GOOGLETEST=/external/path/to/googletest" tools/build-companion.sh "$(pwd)" "$(pwd)/output/"

rather than a more tedious patching of the CMakeFiles.txt and *.cmake files.

Summary of changes:

• external environment variable COMMON_OPTIONS consumed by tools/build-companion.sh