0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

tests/string/strchrnul.c

@@ -0,0 +1,31 @@
+#include <string.h>
+#include <assert.h>
+
+
+int main() {
+    // Test 1: Character is present in the string
+    const char *str1 = "Hello, World!";
+    const char *result1 = strchrnul(str1, 'o');
+    assert(result1 == &str1[4]); // 'o' is at position 4 in "Hello, World!"
+
+    // Test 2: Character is not in the string (should return the null terminator)
+    const char *str2 = "Hello, World!";
+    const char *result2 = strchrnul(str2, 'z');
+    assert(result2 == &str2[13]); // 'z' is not present, so it returns the null terminator
+
+    // Test 3: Character is the first character in the string
+    const char *str3 = "abcdef";
+    const char *result3 = strchrnul(str3, 'a');
+    assert(result3 == &str3[0]); // 'a' is at position 0
+
+    // Test 4: Character is the last character in the string
+    const char *str4 = "abcdef";
+    const char *result4 = strchrnul(str4, 'f');
+    assert(result4 == &str4[5]); // 'f' is at position 5, the last character
+
+    // Test 5: Searching for the null terminator itself
+    const char *str5 = "abcdef";
+    const char *result5 = strchrnul(str5, '\0');
+    assert(result5 == &str5[6]); // The null terminator is at position 6 (end of the string)
+    return 0;
+}