fix bugzilla Issue 24819 - Optimizer changes result of float calculations on 32-bit (dlang/dmd!17023)

(cherry picked from commit 88d1e8fc37428b873f59d87f8dff1f40fbd3e7a3)

Author: WalterBright

tests/dmd/runnable/test24819.d

@@ -0,0 +1,18 @@
+import core.stdc.stdio;
+
+pragma(inline, true)
+double sqrt(double x)
+{
+    static import core.math;
+    return core.math.sqrt(x);
+}
+
+int main()
+{
+    double q = -5.0;
+    double r = q + 1.0;
+    double result = sqrt(-r);
+    //printf("%f\n", result);
+    assert(result == 2);
+    return 0;
+}