Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 6c3e2cc..980cb92 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -7,6 +7,9 @@
 
 void *memdup(const void *src, size_t len);
 
+char **argv_split(const char *str, int *argcp);
+void argv_free(char **argv);
+
 int strtobool(const char *s, bool *res);
 
 /*
@@ -19,6 +22,8 @@
 
 char *str_error_r(int errnum, char *buf, size_t buflen);
 
+char *strreplace(char *s, char old, char new);
+
 /**
  * strstarts - does @str start with @prefix?
  * @str: string to examine
@@ -29,4 +34,8 @@
 	return strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
-#endif /* _LINUX_STRING_H_ */
+extern char * __must_check skip_spaces(const char *);
+
+extern char *strim(char *);
+
+#endif /* _TOOLS_LINUX_STRING_H_ */