tests: Allow running the testsuite on already installed binary / libraries

Currently the test runner script always expects to be run from within the
tests/ subdirectory of a dtc source tree: it looks for dtc and other
binaries in the parent of the current directory and for the libfdt shared
library in ../libfdt.

That works great with make check and for testing a build you've just made.
However, sometimes it's useful to test a dtc & libfdt which have already
been installed on the system, or which for whatever reason are located
somewhere else.

This patch allows the test runner script to do this when TEST_BINDIR and/or
TEST_LIBDIR environment variables are set.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/run_tests.sh

@@ -52,7 +52,10 @@ if [ -z "$STATSZ" ]; then
 fi
 
 # Help things find the libfdt shared object
-export LD_LIBRARY_PATH=../libfdt
+if [ -z "$TEST_LIBDIR" ]; then
+    TEST_LIBDIR=../libfdt
+fi
+export LD_LIBRARY_PATH="$TEST_LIBDIR"
 
 export QUIET_TEST=1
 STOP_ON_FAIL=0

tests/testutils.sh

@@ -18,11 +18,15 @@ FAIL_IF_SIGNAL () {
     fi
 }
 
-DTC=../dtc
-DTGET=../fdtget
-DTPUT=../fdtput
-FDTDUMP=../fdtdump
-FDTOVERLAY=../fdtoverlay
+if [ -z "$TEST_BINDIR" ]; then
+    TEST_BINDIR=..
+fi
+
+DTC=${TEST_BINDIR}/dtc
+DTGET=${TEST_BINDIR}/fdtget
+DTPUT=${TEST_BINDIR}/fdtput
+FDTDUMP=${TEST_BINDIR}/fdtdump
+FDTOVERLAY=${TEST_BINDIR}/fdtoverlay
 
 verbose_run () {
     if [ -z "$QUIET_TEST" ]; then