Build failure was reported in GH#1818 if APPS environment was defined.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1864)
$${ASFLAGS+ASFLAGS} $${AFLAGS+AFLAGS} \
$${LDCMD+LDCMD} $${LDFLAGS+LDFLAGS} $${SCRIPTS+SCRIPTS} \
$${SHAREDCMD+SHAREDCMD} $${SHAREDFLAGS+SHAREDFLAGS} \
- $${SHARED_LIB+SHARED_LIB} $${LIBEXTRAS+LIBEXTRAS}
+ $${SHARED_LIB+SHARED_LIB} $${LIBEXTRAS+LIBEXTRAS} \
+ $${APPS+APPS}
# LC_ALL=C ensures that error [and other] messages are delivered in
# same language for uniform treatment.