Fix missing-prototype errors in tests/suites

Signed-off-by: Michael Schuster <michael@schuster.ms>
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index eb42a07..d28a75e 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -8,7 +8,7 @@
  *
  * \return      0 if success else 1
  */
-int verify_string(char **str)
+static int verify_string(char **str)
 {
     if ((*str)[0] != '"' ||
         (*str)[strlen(*str) - 1] != '"') {
@@ -32,7 +32,7 @@
  *
  * \return      0 if success else 1
  */
-int verify_int(char *str, intmax_t *p_value)
+static int verify_int(char *str, intmax_t *p_value)
 {
     char *end = NULL;
     errno = 0;
@@ -80,7 +80,7 @@
  *
  * \return      0 if success else -1
  */
-int get_line(FILE *f, char *buf, size_t len)
+static int get_line(FILE *f, char *buf, size_t len)
 {
     char *ret;
     int i = 0, str_len = 0, has_string = 0;
@@ -485,7 +485,7 @@
  *
  * \return      Program exit status.
  */
-int execute_tests(int argc, const char **argv)
+static int execute_tests(int argc, const char **argv)
 {
     /* Local Configurations and options */
     const char *default_filename = "DATA_FILE";