[compiler-rt] [builtins] Support building the 128-bit float functions on i386 (PR #122658)

[Alexander Richardson via llvm-commits]

================
@@ -12,7 +12,8 @@
 #define QUAD_PRECISION
 #include "fp_lib.h"
 
-#if defined(CRT_HAS_TF_MODE) && __LDBL_MANT_DIG__ == 64 && defined(__x86_64__)
+#if defined(CRT_HAS_TF_MODE) && __LDBL_MANT_DIG__ == 64 &&                     \
+    (defined(__x86_64__) || defined(__i386__))
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arichardson wrote:

```suggestion
#if defined(CRT_HAS_TF_MODE) && HAS_80_BIT_LONG_DOUBLE
```
As above

https://github.com/llvm/llvm-project/pull/122658