Allow spaces in COB_CC

[ddeclerck]

This (small) PR allows the COB_CC variable to contain spaces, by adding quotes to any sprintf that use it.
Otherwise, one would need to escape all the spaces in COB_CC, and while this is acceptable "in general", this is slightly inconvenient, and besides the other variables do not work this way (for instance try escaping spaces in COB_CONFIG_DIR and you'll see it fails finding the config files - if the path contains spaces).

This of course works as long as COB_CC only contains the path to the C compiler and no argument - which should be the case since arguments should go in COB_CFLAGS & friends.

This would also allow us to get rid of the gcobc wrapper we have in our Windows installer (cf. your comment: "I'd like to know what "gcobc" is"), whose sole purpose is to call cobc with a space-escaped COB_CC.

EDIT: probably needs more work, considering the failures on Windows (had only tested on Linux so far)

[GitMensch]

As you also see in the failing tests - that doesn't work this way as we copy over verbatim what is in the CC variable - and things like -std and -march are commonly set that way.

Note: the more common way is to not use full paths for the binaries but instead prefix its path to PATH.

[GitMensch]

Should we close this (and you prefix PATH with the directory in gcobc)?

[ddeclerck]

Should we close this (and you prefix PATH with the directory in gcobc)?

Yup, let me close this.