cmake: --build supports '-jN'

Source/cmakemain.cxx

.../BuildDir--build--parallel-no-space-bad-number-result.txt

.../BuildDir--build--parallel-no-space-bad-number-stderr.txt

...BuildDir--build--parallel-no-space-good-number-stderr.txt

...parallel-no-space-good-number-trailing--target-stderr.txt

...dLine/BuildDir--build-jobs-no-space-bad-number-result.txt

...dLine/BuildDir--build-jobs-no-space-bad-number-stderr.txt

...Line/BuildDir--build-jobs-no-space-good-number-stderr.txt

...ild-jobs-no-space-good-number-trailing--target-stderr.txt

Tests/RunCMake/CommandLine/RunCMakeTest.cmake