[coverage] enable coverage on toranj tests (#2654)

.travis/script.sh

@@ -368,7 +368,7 @@ set -x
 
 [ $BUILD_TARGET != posix-ncp ] || {
     ./bootstrap || die
-    COVERAGE=1 NODE_TYPE=ncp-sim make -f examples/Makefile-posix check || die
+    NODE_TYPE=ncp-sim make -f examples/Makefile-posix check || die
 }
 
 [ $BUILD_TARGET != toranj-test-framework ] || {

tests/toranj/start.sh

@@ -83,6 +83,7 @@ cd ../..
 ./bootstrap || die
 ./configure                             \
     CPPFLAGS='-DOPENTHREAD_PROJECT_CORE_CONFIG_FILE=\"../tests/toranj/openthread-core-toranj-config.h\"' \
+    --enable-coverage                   \
     --enable-ncp-app=all                \
     --with-ncp-bus=uart                 \
     --with-examples=posix               \