Revert "Use MSVC intrinsic sqrt() on x86 for XBRZ"

This reverts commit 55a0a52a39.

Does not make any difference, the performance issue is elsewhere.

src/filters/xBRZ/xbrz.cpp

@@ -69,6 +69,13 @@ inline double fastSqrt(double n)
 #if (defined(__GNUC__) || defined(__clang__)) && (defined(__x86_64__) || defined(__i386__))
     __asm__ ("fsqrt" : "+t" (n));
     return n;
+#elif defined(_MSC_VER) && defined(_M_IX86)
+    // speeds up xBRZ by about 9% compared to std::sqrt which internally uses
+    // the same assembler instructions but adds some "fluff"
+    __asm {
+        fld n
+        fsqrt
+    }
 #elif defined(_MSC_VER)
     // On MSVC x64 use intrinsic with /Oi and /fp:fast
     return sqrt(n);