scripts: Let generate_source.py be called with a single path #12

Job	Run time
code-format	29s
check_vvl	59s
android (arm64-v8a, ON, c++_shared)	10m 46s
androidOnLinux	12m 57s
chromium (target_os="linux" target_cpu="x64")	7m 42s
android (armeabi-v7a, OFF, c++_static)	8m 56s
linux (address sanitizer, debug, robinhood ON )	28m 47s
chromium (target_os="android" target_cpu="arm64")	10m 38s
linux (address sanitizer, release, robinhood ON )	30m 49s
Ubuntu Backcompat	10m 7s
linux (thread sanitizer, release, robinhood ON )	1h 26m 5s
mingw	10m 55s
linux (address sanitizer, release, robinhood OFF )	32m 3s
windows (amd64)	14m 34s
windows (amd64_x86)	13m 24s
androidUpload	9m 19s
iOS	4m 8s
windowsUpload	20m 54s
linux Upload	18m 25s
	5h 31m 57s

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