iSAC: Untangle some cyclic dependencies

BUG=webrtc:6828, webrtc:7042

Review-Url: https://codereview.webrtc.org/2656823005
Cr-Commit-Position: refs/heads/master@{#16358}

webrtc/modules/audio_coding/codecs/isac/fix/source/fft.c

diff --git a/webrtc/modules/audio_coding/codecs/isac/fix/source/fft.c b/webrtc/modules/audio_coding/codecs/isac/fix/source/fft.c
index 5f91131..21566f1 100644
--- a/webrtc/modules/audio_coding/codecs/isac/fix/source/fft.c
+++ b/webrtc/modules/audio_coding/codecs/isac/fix/source/fft.c
@@ -18,7 +18,7 @@
 
 #include "fft.h"
 
-const int16_t kSortTabFft[240] = {
+static const int16_t kSortTabFft[240] = {
   0, 60, 120, 180, 20, 80, 140, 200, 40, 100, 160, 220,
   4, 64, 124, 184, 24, 84, 144, 204, 44, 104, 164, 224,
   8, 68, 128, 188, 28, 88, 148, 208, 48, 108, 168, 228,
@@ -42,7 +42,7 @@
 };
 
 /* Cosine table in Q14 */
-const int16_t kCosTabFfftQ14[240] = {
+static const int16_t kCosTabFfftQ14[240] = {
   16384,  16378, 16362,   16333,  16294,  16244,  16182,  16110,  16026,  15931,  15826,  15709,
   15582,  15444, 15296,   15137,  14968,  14788,  14598,  14399,  14189,  13970,  13741,  13502,
   13255,  12998, 12733,   12458,  12176,  11885,  11585,  11278,  10963,  10641,  10311,   9974,