Increasing GLOBAL_STACK_SIZE to 120000 to avoid failure

Cannot prove it's the correct value, but it's better than the previous
values, which sometimes segfaults. The increase was made necessary due
to 120 ms frame size support.

celt/arch.h

@@ -260,9 +260,9 @@ static OPUS_INLINE int celt_isnan(float x)
 
 #ifndef GLOBAL_STACK_SIZE
 #ifdef FIXED_POINT
-#define GLOBAL_STACK_SIZE 100000
+#define GLOBAL_STACK_SIZE 120000
 #else
-#define GLOBAL_STACK_SIZE 100000
+#define GLOBAL_STACK_SIZE 120000
 #endif
 #endif