[test-suite] Fix FreeBSD and OpenBSD builds

[dim]

Summary

With clang 16, SingleSource/Benchmarks/Misc/mandel.c fails to compile on
FreeBSD, complaining that hypot() is not declared:

SingleSource/Benchmarks/Misc/mandel.c:38:13: error: call to undeclared library function 'hypot' with type 'double (double, double)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
        if (hypot(__real__ z, __imag__ z) >= ESCAPE)
            ^

The hypot() function is declared in <math.h>, not <complex.h>, so
use the former. This also applies to at least OpenBSD.

[brad]

Looks like all three OS's have tgmath.h as well. Why not just make this

#if defined(__MINGW32__)
#include <complex.h>
#elif defined(__APPLE__)
#include <math.h>
#else
#include <tgmath.h>
#endif

For now, unless you can also build test on macOS?

[dim]

In D146251#4201293, @brad wrote:

Looks like all three OS's have tgmath.h as well. Why not just make this

#if defined(__MINGW32__)
#include <complex.h>
#elif defined(__APPLE__)
#include <math.h>
#else
#include <tgmath.h>
#endif

For now, unless you can also build test on macOS?

Yes, <tgmath.h> is also available on macOS, but it is unnecessary, even on Linux. Using just <math.h> should be sufficient, because the only math function used is hypot(3) which works on doubles by default. There is really no need to pull in the tricky macro machinery from tgmath here.

[brad]

In D146251#4204317, @dim wrote:

Yes, <tgmath.h> is also available on macOS, but it is unnecessary, even on Linux. Using just <math.h> should be sufficient, because the only math function used is hypot(3) which works on doubles by default. There is really no need to pull in the tricky macro machinery from tgmath here.

I was thinking about just using math.h as well but wasn't sure what OS's might be intended to be supported. I started looking through commit history and wasn't sure why tgmath.h was used in the first place.

[dim]

Simplify.

[dim]

Uploaded wrong commit.

SingleSource/Benchmarks/Misc/mandel.c

 #define ESCAPE 2
 #ifdef SMALL_PROBLEM_SIZE
 #define IMAGE_SIZE 500
 #else
 #define IMAGE_SIZE 5000
 #endif
 #define START_X -2.0
 #define START_Y START_X
 #define MAX_ITER 10
 #define step (-START_X - START_X)/IMAGE_SIZE
 
 #define I 1.0iF
 
-#if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__MINGW32__)
+#if defined(__MINGW32__)
 #include <complex.h>
-#elif defined(__APPLE__)
-#include <math.h>
 #else
-#include <tgmath.h>
+#include <math.h>
 #endif
 
 #include <stdio.h>
 
 volatile double __complex__ accum;
 void emit(double __complex__ X) {
   accum += X;
 }