Benchmark, SM2: initialize vars for small stack

Variables may not be initialized in benchmark test when building for
small stack.

Author: SparkiDev

wolfcrypt/benchmark/benchmark.c

@@ -10939,13 +10939,13 @@ void bench_eccEncrypt(int curveId)
 #ifdef WOLFSSL_SM2
 static void bench_sm2_MakeKey(int useDeviceID)
 {
-    int ret = 0, i, times, count, pending = 0;
+    int ret = 0, i, times, count = 0, pending = 0;
     int deviceID;
     int keySize;
     WC_DECLARE_ARRAY(genKey, ecc_key, BENCH_MAX_PENDING,
                      sizeof(ecc_key), HEAP_HINT);
     char name[BENCH_ECC_NAME_SZ];
-    double start;
+    double start = 0;
     const char**desc = bench_desc_words[lng_index];
     DECLARE_MULTI_VALUE_STATS_VARS()
 

wolfssl/wolfcrypt/types.h

@@ -592,7 +592,7 @@ typedef struct w64wrapper {
     #endif
 
     #define WC_DECLARE_HEAP_ARRAY(VAR_NAME, VAR_TYPE, VAR_ITEMS, VAR_SIZE, HEAP) \
-        VAR_TYPE* VAR_NAME[VAR_ITEMS]; \
+        VAR_TYPE* VAR_NAME[VAR_ITEMS] = { NULL, }; \
         int idx##VAR_NAME = 0, inner_idx_##VAR_NAME
     #define WC_HEAP_ARRAY_ARG(VAR_NAME, VAR_TYPE, VAR_ITEMS, VAR_SIZE) \
         VAR_TYPE* VAR_NAME[VAR_ITEMS]