grain_table.c: check fscanf returns for Y/Cr/Cb headers

avoids -Wunused-result warnings

Change-Id: I7fe83b67b12e0c4c6f0d22bc0dc68d374f448035

aom_dsp/grain_table.c

diff --git a/aom_dsp/grain_table.c b/aom_dsp/grain_table.c
index b22752a..03b25c8 100644
--- a/aom_dsp/grain_table.c
+++ b/aom_dsp/grain_table.c
@@ -105,7 +105,11 @@
       }
     }
 
-    fscanf(file, "\n\tcY");
+    if (fscanf(file, "\n\tcY")) {
+      aom_internal_error(error_info, AOM_CODEC_ERROR,
+                         "Unable to read Y coeffs header (cY)");
+      return;
+    }
     const int n = 2 * pars->ar_coeff_lag * (pars->ar_coeff_lag + 1);
     for (int i = 0; i < n; ++i) {
       if (1 != fscanf(file, "%d", &pars->ar_coeffs_y[i])) {
@@ -114,7 +118,11 @@
         return;
       }
     }
-    fscanf(file, "\n\tcCb");
+    if (fscanf(file, "\n\tcCb")) {
+      aom_internal_error(error_info, AOM_CODEC_ERROR,
+                         "Unable to read Cb coeffs header (cCb)");
+      return;
+    }
     for (int i = 0; i <= n; ++i) {
       if (1 != fscanf(file, "%d", &pars->ar_coeffs_cb[i])) {
         aom_internal_error(error_info, AOM_CODEC_ERROR,
@@ -122,7 +130,11 @@
         return;
       }
     }
-    fscanf(file, "\n\tcCr");
+    if (fscanf(file, "\n\tcCr")) {
+      aom_internal_error(error_info, AOM_CODEC_ERROR,
+                         "Unable read to Cr coeffs header (cCr)");
+      return;
+    }
     for (int i = 0; i <= n; ++i) {
       if (1 != fscanf(file, "%d", &pars->ar_coeffs_cr[i])) {
         aom_internal_error(error_info, AOM_CODEC_ERROR,
@@ -130,7 +142,7 @@
         return;
       }
     }
-    fscanf(file, "\n");
+    (void)fscanf(file, "\n");
   }
 }