Make "reverse" noniso conditional on ESP_DSP

Author: me-no-dev

cores/esp32/stdlib_noniso.c

@@ -28,6 +28,23 @@
 #include <stdint.h>
 #include <math.h>
 #include "stdlib_noniso.h"
+#include "esp_system.h"
+
+#if !CONFIG_DSP_ANSI && !CONFIG_DSP_OPTIMIZED
+void reverse(char* begin, char* end) {
+    char *is = begin;
+    char *ie = end - 1;
+    while(is < ie) {
+        char tmp = *ie;
+        *ie = *is;
+        *is = tmp;
+        ++is;
+        --ie;
+    }
+}
+#else
+void reverse(char* begin, char* end);
+#endif
 
 char* ltoa(long value, char* result, int base) {
     if(base < 2 || base > 16) {