Revert r281055 as it breaks installing test scripts in the mixed PROGS/SCRIPT

case

Repro is as follows:

% sudo pkg install -y kyua
% sudo rm -Rf /usr/tests
% sudo make hier
% (cd lib/libthr/tests/; make obj; make depend; make all; sudo make install)
% (cd /usr/tests/lib/libthr; kyua list)

Failure seen in Jenkins build starting here:
https://jenkins.freebsd.org/job/FreeBSD_HEAD-tests2/927/

Pointyhat to: bapt

share/mk/bsd.progs.mk

@@ -96,14 +96,14 @@ x.$p= PROG_CXX=$p
 
 $p ${p}_p: .PHONY .MAKE
 	(cd ${.CURDIR} && ${MAKE} -f ${MAKEFILE} _RECURSING_PROGS= \
-	    SUBDIR= SCRIPTS= PROG=$p \
+	    SUBDIR= PROG=$p \
 	    DEPENDFILE=.depend.$p .MAKE.DEPENDFILE=.depend.$p \
 	    ${x.$p})
 
 .for t in ${PROGS_TARGETS:O:u}
 $p.$t: .PHONY .MAKE
 	(cd ${.CURDIR} && ${MAKE} -f ${MAKEFILE} _RECURSING_PROGS= \
-	    SUBDIR= SCRIPTS= PROG=$p \
+	    SUBDIR= PROG=$p \
 	    DEPENDFILE=.depend.$p .MAKE.DEPENDFILE=.depend.$p \
 	    ${x.$p} ${@:E})
 .endfor