[libc][complex] check that cfloat128 is not defined as _Complex long double (#119324)

Fix buildbot errors in #118671

Author: Sh0g0-1758

libc/include/llvm-libc-types/cfloat128.h

@@ -35,6 +35,7 @@ typedef _Complex _Float128 cfloat128;
 typedef _Complex __float128 cfloat128;
 #elif (LDBL_MANT_DIG == 113)
 #define LIBC_TYPES_HAS_CFLOAT128
+#define LIBC_TYPES_CFLOAT128_IS_COMPLEX_LONG_DOUBLE
 typedef _Complex long double cfloat128;
 #endif
 

libc/src/__support/complex_type.h

@@ -37,10 +37,12 @@ template <> struct make_complex<float16> {
 };
 #endif
 #if defined(LIBC_TYPES_HAS_CFLOAT128)
+#if !(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
 template <> struct make_complex<float128> {
   using type = cfloat128;
 };
 #endif
+#endif
 
 template <typename T> using make_complex_t = typename make_complex<T>::type;
 
@@ -62,10 +64,12 @@ template <> struct make_real<cfloat16> {
 };
 #endif
 #if defined(LIBC_TYPES_HAS_CFLOAT128)
+#if !(LIBC_TYPES_CFLOAT128_IS_COMPLEX_LONG_DOUBLE)
 template <> struct make_real<cfloat128> {
   using type = float128;
 };
 #endif
+#endif
 
 template <typename T> using make_real_t = typename make_real<T>::type;