respect build environment settings

--- zip/unix/configure
+++ zip/unix/configure
@@ -18,7 +18,7 @@
 
 CC=${1-cc}
 CFLAGS=${2-"-I. -DUNIX"}
-LFLAGS1=''
+LFLAGS1="${LDFLAGS}"
 LFLAGS2=''
 LN="ln -s"
 
@@ -118,7 +118,7 @@ _EOF_
 fi
 
 # optimization flags
-if test -n "${CFLAGS_OPT}"; then
+if false; then
   CFLAGS="${CFLAGS} ${CFLAGS_OPT}"
   CFLAGS_BZ="${CFLAGS_BZ} ${CFLAGS_OPT}"
 fi
@@ -220,13 +220,6 @@ fi
 echo Check for the C preprocessor
 # on SVR4, cc -E does not produce correct assembler files. Need /lib/cpp.
 CPP="${CC} -E"
-# solaris as(1) needs -P, maybe others as well ?
-[ -f /usr/ccs/lib/cpp ] && CPP="/usr/ccs/lib/cpp -P"
-[ -f /usr/lib/cpp ] && CPP=/usr/lib/cpp
-[ -f /lib/cpp ] && CPP=/lib/cpp
-[ -f /usr/bin/cpp ] && CPP=/usr/bin/cpp
-[ -f /xenix ] && CPP="${CC} -E"
-[ -f /lynx.os ] && CPP="${CC} -E"
 
 echo "#include <stdio.h>" > conftest.c
 $CPP conftest.c >/dev/null 2>/dev/null || CPP="${CC} -E"