Fix Unicode strings for C++20

u8 strings in C++20 are char8_t instead of char; in order to compile on
both C++17 and C++20 we need to remove the prefix.

Change-Id: I85d1a9d72d24e8fa96ca22b1d99be9982fee8fb5
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/51065
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

crypto/pkcs8/pkcs12_test.cc

diff --git a/crypto/pkcs8/pkcs12_test.cc b/crypto/pkcs8/pkcs12_test.cc
index e67630d..958bd8d 100644
--- a/crypto/pkcs8/pkcs12_test.cc
+++ b/crypto/pkcs8/pkcs12_test.cc
@@ -34,7 +34,7 @@
 static const char kPassword[] = "foo";
 
 // kUnicodePassword is the password for unicode_password.p12
-static const char kUnicodePassword[] = u8"Hello, 世界";
+static const char kUnicodePassword[] = "Hello, 世界";
 
 static bssl::Span<const uint8_t> StringToBytes(const std::string &str) {
   return bssl::MakeConstSpan(reinterpret_cast<const uint8_t *>(str.data()),
@@ -391,7 +391,7 @@
                 {bssl::Span<const uint8_t>(kTestCert2)}, 0, 0, 0, 0);
 
   // Test some Unicode.
-  TestRoundTrip(kPassword, u8"Hello, 世界!",
+  TestRoundTrip(kPassword, "Hello, 世界!",
                 bssl::Span<const uint8_t>(kTestKey),
                 bssl::Span<const uint8_t>(kTestCert),
                 {bssl::Span<const uint8_t>(kTestCert2)}, 0, 0, 0, 0);