lib: Add implementation for strrchr

Signed-off-by: Jaakko Hannikainen <jaakko.hannikainen@intel.com>
Change-Id: I57c549fae0fa8b2321794e9256da63b0a2fe6eaf

lib/libc/minimal/source/string/string.c

diff --git a/lib/libc/minimal/source/string/string.c b/lib/libc/minimal/source/string/string.c
index 7a18e1a..793c10b 100644
--- a/lib/libc/minimal/source/string/string.c
+++ b/lib/libc/minimal/source/string/string.c
@@ -86,6 +86,26 @@
 
 /**
  *
+ * @brief String scanning operation
+ *
+ * @return pointer to last instance of found byte, or NULL if not found
+ */
+
+char *strrchr(const char *s, int c)
+{
+	char *match = NULL;
+
+	do {
+		if (*s == (char)c) {
+			match = (char *)s;
+		}
+	} while (*s++);
+
+	return match;
+}
+
+/**
+ *
  * @brief Get string length
  *
  * @return number of bytes in string <s>