libproc: link against libctf if MK_CTF != no instead of MK_CDDL != no

Logic prior to this change would incorrectly try linking when MK_CDDL != no,
instead of MK_CTF != no, which could result in the library and the tests being
broken if/when MK_CTF == no and MK_CDDL != no (an uncommon, but possible
combination with today's build knobs).

This change updates the conditional to correctly track the value of MK_CTF, which
in turn is properly toggled to no if/when MK_CDDL == no as it's a dependent build
knob.

This [niche] build bug has been present in FreeBSD since 2014.

MFC after:	1 week

lib/libproc/Makefile

@@ -15,7 +15,7 @@ CFLAGS+=	-I${.CURDIR}
 
 LIBADD+=	cxxrt elf procstat rtld_db util z
 
-.if ${MK_CDDL} != "no"
+.if ${MK_CTF} != "no"
 LIBADD+=	ctf
 IGNORE_PRAGMA=	YES
 CFLAGS+= -DIN_BASE

share/mk/src.libnames.mk

@@ -412,7 +412,7 @@ _DP_pam+=	ypclnt
 _DP_pfctl=	nv
 _DP_pjdlog=	util
 _DP_proc=	cxxrt
-.if ${MK_CDDL} != "no"
+.if ${MK_CTF} != "no"
 _DP_proc+=	ctf
 .endif
 _DP_proc+=	elf procstat rtld_db util z