fft: avoid a signed overflow

As a signed integer, 1<<31 overflows, so force it to unsigned.
Signed-off-by: Alex Converse <alex.converse@gmail.com>

libavcodec/x86/fft_3dn2.c

@@ -23,7 +23,7 @@
 #include "libavcodec/dsputil.h"
 #include "fft.h"
 
-DECLARE_ALIGNED(8, static const int, m1m1)[2] = { 1<<31, 1<<31 };
+DECLARE_ALIGNED(8, static const unsigned int, m1m1)[2] = { 1U<<31, 1U<<31 };
 
 #ifdef EMULATE_3DNOWEXT
 #define PSWAPD(s,d)\
@@ -70,7 +70,7 @@ void ff_imdct_half_3dn2(FFTContext *s, FFTSample *output, const FFTSample *input
     in1 = input;
     in2 = input + n2 - 1;
 #ifdef EMULATE_3DNOWEXT
-    __asm__ volatile("movd %0, %%mm7" ::"r"(1<<31));
+    __asm__ volatile("movd %0, %%mm7" ::"r"(1U<<31));
 #endif
     for(k = 0; k < n4; k++) {
         // FIXME a single block is faster, but gcc 2.95 and 3.4.x on 32bit can't compile it

libavcodec/x86/fft_sse.c

@@ -24,8 +24,8 @@
 #include "fft.h"
 #include "config.h"
 
-DECLARE_ASM_CONST(16, int, ff_m1m1m1m1)[4] =
-    { 1 << 31, 1 << 31, 1 << 31, 1 << 31 };
+DECLARE_ASM_CONST(16, unsigned int, ff_m1m1m1m1)[4] =
+    { 1U << 31, 1U << 31, 1U << 31, 1U << 31 };
 
 void ff_fft_dispatch_sse(FFTComplex *z, int nbits);
 void ff_fft_dispatch_interleave_sse(FFTComplex *z, int nbits);