Treat the char [DHOP] after a single quote as special only in Vera language

In Vera language a single quote is used as prefix for number literals.
(See Units/jbrown.vr.t/input.vr as an example.)

In languages defined in c.c other than Vera, the character [DHCP]
after single quote doesn't have no special meaning. However, the old
code treats the char as special even if the language is other than Vera.
"Error parsing C/CPP files when certain element is present #179" spots
a bug trigger by the old code.

With this change, a parser can pass the usage of the single quote in
the language to get.c via cppInit.

Suggested by @b4n.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
units: add a test case for "Error parsing C/CPP files when certain element is present #179"

Signed-off-by: Masatake YAMATO <yamato@redhat.com>