Put SIMD perf warnings behind a flag

It's not always realistic to update your compiler, and these warings constantly flood the terminal if you can't. Put them behind a flag. We can always turn the flag back on locally to check a specific target.

Diffs=
12285f625 Put SIMD perf warnings behind a flag (#4861)

.rive_head

diff --git a/.rive_head b/.rive_head
index 726c613..5bc4085 100644
--- a/.rive_head
+++ b/.rive_head
@@ -1 +1 @@
-157a399d23a0f5ea729ad50661f88eea8f84eee1
+12285f625ff69c6b21528d93b3b665d9b0b9f8be

include/rive/math/simd.hpp

diff --git a/include/rive/math/simd.hpp b/include/rive/math/simd.hpp
index 2ee5a4e..7f45c24 100644
--- a/include/rive/math/simd.hpp
+++ b/include/rive/math/simd.hpp
@@ -14,6 +14,8 @@
 #ifndef _RIVE_SIMD_HPP_
 #define _RIVE_SIMD_HPP_
 
+// #define RIVE_SIMD_PERF_WARNINGS
+
 #include "rive/rive_types.hpp"
 #include <cassert>
 #include <limits>
@@ -50,7 +52,9 @@
 #else
 
 // gvec needs to be polyfilled with templates.
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: ext_vector_type not supported. Consider using clang.")
+#endif
 #include "simd_gvec_polyfill.hpp"
 
 #endif
@@ -71,7 +75,9 @@
 #if __has_builtin(__builtin_reduce_or)
     return __builtin_reduce_or(x);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_reduce_or() not supported. Consider updating clang.")
+#endif
     // This particular logic structure gets decent codegen in clang.
     for (int i = 0; i < N; ++i)
     {
@@ -88,7 +94,9 @@
 #if __has_builtin(__builtin_reduce_and)
     return __builtin_reduce_and(x);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_reduce_and() not supported. Consider updating clang.")
+#endif
     // In vector, true is represented by -1 exactly, so we use ~x for "not".
     return !any(~x);
 #endif
@@ -118,7 +126,9 @@
     // The '?:' operator supports a vector condition beginning in clang 13.
     return _if ? _then : _else;
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: vectorized '?:' operator not supported. Consider updating clang.")
+#endif
     gvec<T, N> ret{};
     for (int i = 0; i < N; ++i)
         ret[i] = _if[i] ? _then[i] : _else[i];
@@ -133,7 +143,9 @@
 #if __has_builtin(__builtin_elementwise_min)
     return __builtin_elementwise_min(a, b);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_elementwise_min() not supported. Consider updating clang.")
+#endif
     // Generate the same behavior for NaN as the SIMD builtins. (isnan() is a no-op for int types.)
     return if_then_else(b < a || isnan(a), b, a);
 #endif
@@ -146,7 +158,9 @@
 #if __has_builtin(__builtin_elementwise_max)
     return __builtin_elementwise_max(a, b);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_elementwise_max() not supported. Consider updating clang.")
+#endif
     // Generate the same behavior for NaN as the SIMD builtins. (isnan() is a no-op for int types.)
     return if_then_else(a < b || isnan(a), b, a);
 #endif
@@ -171,7 +185,9 @@
 #if __has_builtin(__builtin_elementwise_abs)
     return __builtin_elementwise_abs(x);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_elementwise_abs() not supported. Consider updating clang.")
+#endif
     return if_then_else(x < (T)0, -x, x); // Negate on the "true" side so we never negate NaN.
 #endif
 }
@@ -204,8 +220,10 @@
 #if __has_builtin(__builtin_elementwise_floor)
     return __builtin_elementwise_floor(x);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message(                                                                                   \
     "performance: __builtin_elementwise_floor() not supported. Consider updating clang.")
+#endif
     for (int i = 0; i < N; ++i)
         x[i] = floorf(x[i]);
     return x;
@@ -217,7 +235,9 @@
 #if __has_builtin(__builtin_elementwise_ceil)
     return __builtin_elementwise_ceil(x);
 #else
+#ifdef RIVE_SIMD_PERF_WARNINGS
 #pragma message("performance: __builtin_elementwise_ceil() not supported. Consider updating clang.")
+#endif
     for (int i = 0; i < N; ++i)
         x[i] = ceilf(x[i]);
     return x;