Add a regression test for EC bitmap recovery losing a parity chunk

src/util/str_util.cpp

@@ -518,3 +518,11 @@ bool is_zero(void *buf, size_t size)
     }
     return true;
 }
+
+bool memcheck(uint8_t *buf, uint8_t byte, size_t len)
+{
+    for (size_t i = 0; i < len; i++)
+        if (buf[i] != byte)
+            return false;
+    return true;
+}

src/util/str_util.h

@@ -35,5 +35,6 @@ std::string realpath_str(std::string path, bool nofail = true);
 std::string strprintf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
 std::string format_datetime(uint64_t unixtime);
 bool is_zero(void *buf, size_t size);
+bool memcheck(uint8_t *buf, uint8_t byte, size_t len);
 
 #pragma GCC visibility pop