test: fix possible artifacts in unicode_api

Travis sometimes reports a function 'invalid' to not have U/W versions.
Add vmem_stats_print to the exclude list, it does not need to have
U/W versions.

src/test/unicode_api/TEST0

@@ -50,15 +50,15 @@ require_command clang
 SRC=../..
 HEADERS_DIR=$SRC/include
 INC_DIR=$SRC/include/libpmemobj
-EXC_PATT="set_funcs|strdup|rpmem"
+EXC_PATT="set_funcs|strdup|rpmem|vmem_stats_print"
 FAILED=0
 
 function check_file {
 	local file=$1
 	local dir=$2
 	local pat=$3
 
-	local funcs=$(clang -Xclang -ast-dump $file -fno-color-diagnostics 2> /dev/null |\
+	local funcs=$(clang -Xclang -ast-dump -I$HEADERS_DIR $file -fno-color-diagnostics 2> /dev/null |\
 		grep "FunctionDecl.*\(vmem\|pmem\).*char \*" | cut -d " " -f 6)
 	for func in $funcs
 	do