variable to NULL, to avoid using it uninitialized in certain cases.
This fixes the following clang 3.2 warning:
usr.bin/make/var.c:1770:10: error: variable 'error' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
if (vp->execute) {
^~~~~~~~~~~
usr.bin/make/var.c:1777:10: note: uninitialized use occurs here
if (error)
^~~~~
usr.bin/make/var.c:1770:6: note: remove the 'if' if its condition is always true
if (vp->execute) {
^~~~~~~~~~~~~~~~~
usr.bin/make/var.c:1768:23: note: initialize the variable 'error' to silence this warning
const char *error;
^
= NULL
MFC after: 1 week
