fix(printf): suppress terminating \0 in printf() output

Closes #19

printf.c

@@ -104,7 +104,9 @@ static inline void _out_null(char character, char* buffer, size_t idx, size_t ma
 static inline void _out_char(char character, char* buffer, size_t idx, size_t maxlen)
 {
   (void)buffer; (void)idx; (void)maxlen;
-  _putchar(character);
+  if (character) {
+    _putchar(character);
+  }
 }
 
 

test/test_suite.cpp

@@ -55,11 +55,12 @@ void _out_fct(char character, void* arg)
 }
 
 
-
 TEST_CASE("printf", "[]" ) {
   printf_idx = 0U;
   memset(printf_buffer, 0xCC, 100U);
   REQUIRE(test::printf("% d", 4232) == 5);
+  REQUIRE(printf_buffer[5] == (char)0xCC);
+  printf_buffer[5] = 0;
   REQUIRE(!strcmp(printf_buffer, " 4232"));
 }