[liba] Proper support for function-like macros for math functions

liba/src/external/openbsd/include/math.h

@@ -0,0 +1,66 @@
+#include_next <math.h>
+
+/* In accordance with the C99 standard, we've defined libm function as macros to
+ * leverage compiler optimizations. When comes the time to actually implement
+ * those functions, we don't want the macro to be active. OpenBSD doesn't use
+ * macros so it doesn't bother #undef-ing libm functions. Let's do it here. */
+
+#undef acosf
+#undef acoshf
+#undef asinf
+#undef asinhf
+#undef atanf
+#undef atan2f
+#undef atanhf
+#undef ceilf
+#undef copysignf
+#undef cosf
+#undef coshf
+#undef expf
+#undef expm1f
+#undef fabsf
+#undef floorf
+#undef fmodf
+#undef lgammaf
+#undef lgammaf_r
+#undef log1pf
+#undef log10f
+#undef logf
+#undef nanf
+#undef nearbyintf
+#undef powf
+#undef roundf
+#undef scalbnf
+#undef sinf
+#undef sinhf
+#undef sqrtf
+#undef tanf
+#undef tanhf
+
+#undef acos
+#undef acosh
+#undef asin
+#undef asinh
+#undef atan
+#undef atanh
+#undef ceil
+#undef copysign
+#undef cos
+#undef cosh
+#undef exp
+#undef expm1
+#undef fabs
+#undef floor
+#undef lgamma
+#undef lgamma_r
+#undef log1p
+#undef log10
+#undef log
+#undef pow
+#undef round
+#undef scalbn
+#undef sin
+#undef sinh
+#undef sqrt
+#undef tan
+#undef tanh

liba/src/nearbyintf.c

@@ -1,5 +1,7 @@
 #include <math.h>
 
+#undef nearbyintf
+
 /* nearbyintf is not supposed to be the same as roundf according to openBSD
  * documentation. Indeed:
  * - they round halfway cases to the nearest integer instead of away from zero