define and export LOG_TEST_FILENAME

Otherwise the cppcheck script is not able to store log as seen below:

		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 54: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 55: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 56: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 60: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 61: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 62: : No such file or directory
		./tf-a-ci-scripts/script/static-checks/static-checks-cppcheck.sh: line 64: : No such file or directory

Change-Id: I3df6896326741f9e5fff826b1c91cd15ba2fca9b
Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
diff --git a/script/static-checks/static-checks-cppcheck.sh b/script/static-checks/static-checks-cppcheck.sh
index 7f5ed8f..40d161f 100755
--- a/script/static-checks/static-checks-cppcheck.sh
+++ b/script/static-checks/static-checks-cppcheck.sh
@@ -11,6 +11,8 @@
 
 TF_BASE="$(pwd)"
 
+export LOG_TEST_FILENAME=$(pwd)/static-checks-cppcheck.log
+
 # cppcheck configuration
 COMMON_ARGS=(-j 16 -q -f --std=c99 --error-exitcode=1 --relative-paths="$TF_BASE")
 CHECKS_ARGS=(--enable=warning,style,portability)