Revert "libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8"

This reverts commit 53473c160713b8605e262bf212b0cf5e9a19a4d6.

Change-Id: I27379317e08ecbd5e3b95b7ece58194838ab6c21
diff --git a/include/utils/Unicode.h b/include/utils/Unicode.h
index f96c99e..c8c87c3 100644
--- a/include/utils/Unicode.h
+++ b/include/utils/Unicode.h
@@ -90,7 +90,7 @@
  * "dst" becomes \xE3\x81\x82\xE3\x81\x84
  * (note that "dst" is NOT null-terminated, like strncpy)
  */
-void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len);
+void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst);
 
 /**
  * Returns the unicode value at "index".
@@ -112,7 +112,7 @@
  * enough to fit the UTF-16 as measured by utf16_to_utf8_length with an added
  * NULL terminator.
  */
-void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len);
+void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst);
 
 /**
  * Returns the length of "src" when "src" is valid UTF-8 string.