fix msvc build (#3857, #3771)

code/libspeex/include/speex/config.h

@@ -0,0 +1,20 @@
+// Microsoft version of 'inline'
+#define inline __inline
+
+// Visual Studio support alloca(), but it always align variables to 16-bit
+// boundary, while SSE need 128-bit alignment. So we disable alloca() when
+// SSE is enabled.
+#ifndef _USE_SSE
+#  define USE_ALLOCA
+#endif
+
+/* Default to floating point */
+#ifndef FIXED_POINT
+#  define FLOATING_POINT
+#  define USE_SMALLFT
+#else
+#  define USE_KISS_FFT
+#endif
+
+/* We don't support visibility on Win32 */
+#define EXPORT