Add GPL headers to qrduino benchmark.

The original source,  https://github.com/tz1/qrduino, is GPL.

ChangeLog:

	* src/qrduino/qrtest.c: Update GPL header to correct benchmark
	name.
	* src/qrduino/ecctable.h: Add GPL header.
	* src/qrduino/qrbits.h: Add GPL header.
	* src/qrduino/qrencode.c: Add GPL header.
	* src/qrduino/qrencode.h: Add GPL header.
	* src/qrduino/qrframe.c: Add GPL header.