build system: rm unused variable declarations from Mamfiles

Now that the Make Abstract Machine files are maintained manually
and not generated automatically, unused variables are an annoying
distraction -- and there are many.

But the language/format is very simple and very parseable using
shell, awk, etc. -- so this was easy to automate. All variables are
declared with 'setv' and they are used if an expansion of the form
${varname} exists (the braces are mandatory in Mamfiles).

bin/Mamfile_rm_unused_vars:
- Added for reference and future use.

src/*/*/Mamfile:
- Remove all unused 'setv' variable declarations.

src/cmd/ksh93/Mamfile

@@ -10,12 +10,8 @@ note * http://web.archive.org/web/20041227143022/http://www2.research.att.com/~g
 note *
 setv INSTALLROOT ../../..
 setv PACKAGE_ast_INCLUDE ${INSTALLROOT}/include/ast
-setv PACKAGE_ast_LIB ${INSTALLROOT}/lib
 setv PACKAGEROOT ../../../../..
 setv AR ${mam_cc_AR} ${mam_cc_AR_ARFLAGS}
-setv ARFLAGS rc
-setv AS as
-setv ASFLAGS
 setv CC cc
 setv mam_cc_FLAGS
 setv KSH_RELFLAGS
@@ -23,30 +19,9 @@ setv KSH_SHOPTFLAGS
 setv CCFLAGS ${-debug-symbols?1?${mam_cc_DEBUG} -D_BLD_DEBUG?${mam_cc_OPTIMIZE}?}
 setv CCLDFLAGS ${-strip-symbols?1?${mam_cc_LD_STRIP}??}
 setv COTEMP $$
-setv CPIO cpio
-setv CPIOFLAGS
-setv CPP "${CC} -E"
-setv F77 f77
-setv HOSTCC ${CC}
 setv IFFEFLAGS
-setv IGNORE
-setv LD ld
 setv LDFLAGS
-setv LEX lex
-setv LEXFLAGS
-setv LPR lpr
-setv LPRFLAGS
-setv M4FLAGS
-setv NMAKE nmake
-setv NMAKEFLAGS
-setv PR pr
-setv PRFLAGS
 setv SH_DICT \"libshell\"
-setv SHELL /bin/sh
-setv SILENT
-setv TAR tar
-setv YACC yacc
-setv YACCFLAGS -d
 make ${PACKAGEROOT}/lib/package/ast.lic
 done ${PACKAGEROOT}/lib/package/ast.lic
 make install
@@ -1412,9 +1387,6 @@ make install
 			meta shcomp.o %.c>%.o sh/shcomp.c shcomp
 			prev sh/shcomp.c
 			prev SHOPT.sh
-			setv CC.DLL -UCC.DLL
-			setv _BLD_shell -U_BLD_shell
-			setv _BLD_DLL -U_BLD_DLL
 			exec - ${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${KSH_SHOPTFLAGS} ${CCFLAGS} -I. -Iinclude -I${PACKAGE_ast_INCLUDE} -DSH_DICT=${SH_DICT} -D_API_ast=20100309 -D_PACKAGE_ast -DERROR_CONTEXT_T=Error_context_t -c sh/shcomp.c
 		done shcomp.o generated
 		prev libshell.a archive
@@ -1422,7 +1394,6 @@ make install
 		prev +li
 		prev ${mam_libsocket}
 		prev ${mam_libsecdb}
-		setv CC.DLL -UCC.DLL
 		exec - ${CC} ${CCLDFLAGS} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${KSH_SHOPTFLAGS} ${CCFLAGS} ${LDFLAGS} ${mam_cc_L+-L.} ${mam_cc_L+-L${INSTALLROOT}/lib} -o shcomp shcomp.o ${mam_libshell} ${mam_libnsl} ${mam_libast}
 	done shcomp generated
 	make suid_exec
@@ -1438,15 +1409,12 @@ make install
 			meta suid_exec.o %.c>%.o sh/suid_exec.c suid_exec
 			prev sh/suid_exec.c
 			prev SHOPT.sh
-			setv CC.DLL -UCC.DLL
-			setv _BLD_shell -U_BLD_shell
 			exec - ${CC} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${KSH_SHOPTFLAGS} ${CCFLAGS} -I. -Iinclude -I${PACKAGE_ast_INCLUDE} -DERROR_CONTEXT_T=Error_context_t -D_API_ast=20100309 -D_PACKAGE_ast -c sh/suid_exec.c
 		done suid_exec.o generated
 		prev +ljobs
 		prev +li
 		prev ${mam_libsocket}
 		prev ${mam_libsecdb}
-		setv CC.DLL -UCC.DLL
 		exec - ${CC} ${CCLDFLAGS} ${mam_cc_FLAGS} ${KSH_RELFLAGS} ${KSH_SHOPTFLAGS} ${CCFLAGS} ${LDFLAGS} -lm ${mam_cc_L+-L.} ${mam_cc_L+-L${INSTALLROOT}/lib} -o suid_exec suid_exec.o ${mam_libast} ${mam_libnsl} ${mam_libast}
 	done suid_exec generated
 	make shell
@@ -1558,19 +1526,16 @@ make install
 		prev ${INSTALLROOT}/fun
 		make fun/dirs
 		done fun/dirs
-		setv mode -Dmode="+x"
 		exec - test '' = 'fun/dirs' || ${STDCMP} 2>/dev/null -s fun/dirs ${INSTALLROOT}/fun/dirs || { ${STDMV} ${INSTALLROOT}/fun/dirs ${INSTALLROOT}/fun/dirs.old 2>/dev/null || true; ${STDCP} fun/dirs ${INSTALLROOT}/fun/dirs && chmod ugo+x ${INSTALLROOT}/fun/dirs ;}
 	done ${INSTALLROOT}/fun/dirs generated
 	make ${INSTALLROOT}/fun/popd
 		make fun/popd
 		done fun/popd
-		setv mode -Dmode="+x"
 		exec - test '' = 'fun/popd' || ${STDCMP} 2>/dev/null -s fun/popd ${INSTALLROOT}/fun/popd || { ${STDMV} ${INSTALLROOT}/fun/popd ${INSTALLROOT}/fun/popd.old 2>/dev/null || true; ${STDCP} fun/popd ${INSTALLROOT}/fun/popd && chmod ugo+x ${INSTALLROOT}/fun/popd ;}
 	done ${INSTALLROOT}/fun/popd generated
 	make ${INSTALLROOT}/fun/pushd
 		make fun/pushd
 		done fun/pushd
-		setv mode -Dmode="+x"
 		exec - test '' = 'fun/pushd' || ${STDCMP} 2>/dev/null -s fun/pushd ${INSTALLROOT}/fun/pushd || { ${STDMV} ${INSTALLROOT}/fun/pushd ${INSTALLROOT}/fun/pushd.old 2>/dev/null || true; ${STDCP} fun/pushd ${INSTALLROOT}/fun/pushd && chmod ugo+x ${INSTALLROOT}/fun/pushd ;}
 	done ${INSTALLROOT}/fun/pushd generated
 done install virtual