Fix Makefile help (#381)
Fix Makefile help (#381)

AWK's `[[:space:]]` clause doesn't work on Linux, but works on MacOS.

Use space symbol instead which works well with both AWK implementations.
cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra,cossacklabs/acra