Make some build scripts robust in case CDPATH is set and inconvenient.

CDPATH isn't supposed to be exported, but it can be; and POSIX says cd
should always use PWD after searching CDPATH, but some recent OS
releases still ship versions of /bin/sh that don't. So let's have our
build scripts continue to be explicit about where they're cd'ing to.

INSTALL

@@ -139,11 +139,11 @@ INSTALLING SBCL
 
   To run the regression tests:
 
-    $ cd tests && sh run-tests.sh
+    $ cd ./tests && sh run-tests.sh
 
   To build documentation:
 
-    $ cd doc/manual && make
+    $ cd ./doc/manual && make
 
   This builds the Info, HTML and PDF documentation from the Texinfo
   sources. The manual includes documentation string from the build

make-target-contrib.sh

@@ -73,7 +73,7 @@ fi
 
 # Otherwise report expected failures:
 HEADER_HAS_BEEN_PRINTED=false
-for dir in `cd obj/asdf-cache/ ; echo *`; do
+for dir in `cd ./obj/asdf-cache/ ; echo *`; do
   f="obj/asdf-cache/$dir/test-passed.test-report"
   if test -f "$f" && grep -i fail "$f" >/dev/null; then
       if ! $HEADER_HAS_BEEN_PRINTED; then
@@ -90,7 +90,7 @@ EOF
 done
 
 if [ -z "$*" ]; then
-    contribs_to_build="`cd contrib ; echo *`"
+    contribs_to_build="`cd ./contrib ; echo *`"
 else
     contribs_to_build="$*"
 fi

make-windows-installer.sh

@@ -12,7 +12,7 @@
 WIX_PATH=$WIX/bin
 
 SBCL_TOP=../
-cd output
+cd ./output
 
 "$SBCL_TOP/src/runtime/sbcl" --noinform --core "$SBCL_TOP/output/sbcl.core" \
   --disable-debugger --no-sysinit --no-userinit \

make.sh

@@ -93,11 +93,11 @@ echo "The build seems to have finished successfully, including $NPASSED (out of
 echo "contributed modules. If you would like to run more extensive tests on"
 echo "the new SBCL, you can try:"
 echo
-echo "  cd tests && sh ./run-tests.sh"
+echo "  cd ./tests && sh ./run-tests.sh"
 echo
 echo "To build documentation:"
 echo
-echo "  cd doc/manual && make"
+echo "  cd ./doc/manual && make"
 echo
 echo "To install SBCL (more information in INSTALL):"
 echo