[NFC][sanitizer] Remove InternalScopedString::Append nullptr workaround

AppendF actually appends "<null>" which is not needed here.

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp

@@ -338,8 +338,6 @@ int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 }
 
 void InternalScopedString::Append(const char *str) {
-  if (!str)  // For consistency with AppendF("%s", str) which accepts nullptr.
-    return;
   uptr prev_len = length();
   uptr str_len = internal_strlen(str);
   buffer_.resize(prev_len + str_len + 1);

compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp

@@ -381,10 +381,6 @@ TEST(SanitizerCommon, InternalScopedStringAppend) {
   EXPECT_EQ(0U, str.length());
   EXPECT_STREQ("", str.data());
 
-  str.Append(nullptr);
-  EXPECT_EQ(0U, str.length());
-  EXPECT_STREQ("", str.data());
-
   str.Append("");
   EXPECT_EQ(0U, str.length());
   EXPECT_STREQ("", str.data());