Import bmake-20230622

Import bmake-20230622

Relevant/interesting changes:

	o optimize string matching for ':M' and ':N'
	o warn about malformed patterns in ':M', ':N' and '.if make(...)'
	o allow guards to be targets as well as variables
	The guard targets may include variable references like
	__${.PARSEDIR:tA}/${.PARSEFILE}__
	o optimization for makefiles protected from multiple-inclusion
	skip even opening the file after first include.
	o var.c: do not allow delete of readOnly variable
	o parse.c: .break takes no args