ci: run CMake in script mode when finding source files

Author: igrr

Diff for: .github/scripts/check-cmakelists.sh

@@ -15,7 +15,7 @@ git submodule update --init --recursive
 REPO_SRCS=`find cores/esp32/ libraries/ -name 'examples' -prune -o -name '*.c' -print -o -name '*.cpp' -print | sort`
 
 # find all source files named in CMakeLists.txt COMPONENT_SRCS
-CMAKE_SRCS=`cmake --trace-expand -C CMakeLists.txt 2>&1 | grep set\(srcs | cut -d'(' -f3 | sed 's/ )//' | sed 's/srcs //' | tr ' ;' '\n' | sort`
+CMAKE_SRCS=`cmake --trace-expand -P CMakeLists.txt 2>&1 | grep set\(srcs | cut -d'(' -f3 | sed 's/ )//' | sed 's/srcs //' | tr ' ;' '\n' | sort`
 
 if ! diff -u0 --label "Repo Files" --label "srcs" <(echo "$REPO_SRCS") <(echo "$CMAKE_SRCS"); then
     echo "Source files in repo (-) and source files in CMakeLists.txt (+) don't match"