previous commit:
+ Everything is initialized using ?= instead of =.
+ Nicer formatting (more white space).
+ .c: rule.
Add macros ECHO and ECHODIR. Both are normally `echo', but when
the make flags include -s, ECHO is set to `true' and when the make
flags include two or more -s's ECHODIR is set to `true'. @${ECHO}
should be used instead of @echo in most cases. ${ECHODIR} is
intended to be used mainly for messages about directory names.
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