use WEBP_DSP_INIT_FUNC for Init{GammaTables*,GetCoeffs}

this provides stronger synchronization when pthreads are available as
was done in 'd77bf512 add WEBP_DSP_INIT / WEBP_DSP_INIT_FUNC' for the
other init functions.

Change-Id: I2ffe4e24454d276c2411ece34dca38d23d4756d5
diff --git a/src/dec/vp8_dec.c b/src/dec/vp8_dec.c
index 57efb69..8f73697 100644
--- a/src/dec/vp8_dec.c
+++ b/src/dec/vp8_dec.c
@@ -494,13 +494,11 @@
   return 16;
 }
 
-static WEBP_TSAN_IGNORE_FUNCTION void InitGetCoeffs(void) {
-  if (GetCoeffs == NULL) {
-    if (VP8GetCPUInfo != NULL && VP8GetCPUInfo(kSlowSSSE3)) {
-      GetCoeffs = GetCoeffsAlt;
-    } else {
-      GetCoeffs = GetCoeffsFast;
-    }
+WEBP_DSP_INIT_FUNC(InitGetCoeffs) {
+  if (VP8GetCPUInfo != NULL && VP8GetCPUInfo(kSlowSSSE3)) {
+    GetCoeffs = GetCoeffsAlt;
+  } else {
+    GetCoeffs = GetCoeffsFast;
   }
 }
 
diff --git a/src/enc/picture_csp_enc.c b/src/enc/picture_csp_enc.c
index 718e014..368837b 100644
--- a/src/enc/picture_csp_enc.c
+++ b/src/enc/picture_csp_enc.c
@@ -90,8 +90,9 @@
 static int kLinearToGammaTab[kGammaTabSize + 1];
 static uint16_t kGammaToLinearTab[256];
 static volatile int kGammaTablesOk = 0;
+static void InitGammaTables(void);
 
-static WEBP_TSAN_IGNORE_FUNCTION void InitGammaTables(void) {
+WEBP_DSP_INIT_FUNC(InitGammaTables) {
   if (!kGammaTablesOk) {
     int v;
     const double scale = (double)(1 << kGammaTabFix) / kGammaScale;
@@ -181,8 +182,9 @@
 #define GAMMA_TO_LINEAR_BITS 14
 static uint32_t kGammaToLinearTabS[MAX_Y_T + 1];   // size scales with Y_FIX
 static volatile int kGammaTablesSOk = 0;
+static void InitGammaTablesS(void);
 
-static WEBP_TSAN_IGNORE_FUNCTION void InitGammaTablesS(void) {
+WEBP_DSP_INIT_FUNC(InitGammaTablesS) {
   assert(2 * GAMMA_TO_LINEAR_BITS < 32);  // we use uint32_t intermediate values
   if (!kGammaTablesSOk) {
     int v;