math: use sqrtl if FLT_EVAL_METHOD==2 in acosh and acoshf

this makes acosh slightly more precise around 1.0 on i386

src/math/acosh.c

 #include "libm.h"
 
+#if FLT_EVAL_METHOD==2
+#undef sqrt
+#define sqrt sqrtl
+#endif
+
 /* acosh(x) = log(x + sqrt(x*x-1)) */
 double acosh(double x)
 {

src/math/acoshf.c

 #include "libm.h"
 
+#if FLT_EVAL_METHOD==2
+#undef sqrtf
+#define sqrtf sqrtl
+#elif FLT_EVAL_METHOD==1
+#undef sqrtf
+#define sqrtf sqrt
+#endif
+
 /* acosh(x) = log(x + sqrt(x*x-1)) */
 float acoshf(float x)
 {