[compiler-rt] Make builtins test pass when using i386 gcc as host compiler

[thakis]

Summary

Just-built-clang is used to compile the test, but the library is built with gcc, so the usual 80-bit FPU vs 32-bit SSE mismatch makes the floating computations not bitwise identical. See PR32910 for details.

This uses the same technique used in all the other *c3* tests, see in particular mulsc3_test.c.

(It might be cleaner to add compareResultCF to fp_test.h to force the floats into 32-bit in memory, but this is the less invasive fix.)

compiler-rt/trunk/test/builtins/Unit/divsc3_test.c

case non_zero:
                 return 1;
             break;
         case non_zero:
             if (classify(r) != non_zero)
                 return 1;
             {
             float _Complex z = (a * c + b * d) / (c * c + d * d)
                              + (b * c - a * d) / (c * c + d * d) * _Complex_I;
-            if (r != z)
+            if (cabsf((r-z)/r) > 1.e-6)
                 return 1;
             }
             break;
         case inf:
             if (classify(r) != zero)
                 return 1;
             break;
         case NaN: