treewide: Various fixes for clang compilation

Change-Id: I37e53e3854687ffeb146db515c2de69b2e6ac02d
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/fd/fmt.cpp b/test/fd/fmt.cpp
index 770bc99..9448fed 100644
--- a/test/fd/fmt.cpp
+++ b/test/fd/fmt.cpp
@@ -15,7 +15,6 @@
 namespace fd
 {
 
-using fmt::operator""_cf;
 using std::literals::string_view_literals::operator""sv;
 
 TEST(FormatBuffer, Basic)
@@ -31,7 +30,7 @@
         EXPECT_EQ(6, fd.lseek(0, Whence::Cur));
         buf.append(FMT_COMPILE("{}"), std::string(2050, 'a'));
         EXPECT_EQ(6, fd.lseek(0, Whence::Cur));
-        buf.append("{}"_cf, std::string(2050, 'a'));
+        buf.append(FMT_COMPILE("{}"), std::string(2050, 'a'));
         EXPECT_EQ(4106, fd.lseek(0, Whence::Cur));
 
         buf.append(FMT_STRING("hi\n"));