Use c++ strings

Author: NicolasHug

src/torchcodec/_core/FFMPEGCommon.cpp

@@ -5,7 +5,6 @@
 // LICENSE file in the root directory of this source tree.
 
 #include "src/torchcodec/_core/FFMPEGCommon.h"
-#include <cstdlib>
 
 #include <c10/util/Exception.h>
 
@@ -161,25 +160,26 @@ SwrContext* allocateSwrContext(
 
 void setFFmpegLogLevel() {
   auto logLevel = AV_LOG_QUIET;
-  const char* logLevelEnv = std::getenv("TORCHCODEC_FFMPEG_LOG_LEVEL");
-  if (logLevelEnv != nullptr) {
-    if (std::strcmp(logLevelEnv, "QUIET") == 0) {
+  const char* logLevelEnvPtr = std::getenv("TORCHCODEC_FFMPEG_LOG_LEVEL");
+  if (logLevelEnvPtr != nullptr) {
+    std::string logLevelEnv(logLevelEnvPtr);
+    if (logLevelEnv == "QUIET") {
       logLevel = AV_LOG_QUIET;
-    } else if (std::strcmp(logLevelEnv, "PANIC") == 0) {
+    } else if (logLevelEnv == "PANIC") {
       logLevel = AV_LOG_PANIC;
-    } else if (std::strcmp(logLevelEnv, "FATAL") == 0) {
+    } else if (logLevelEnv == "FATAL") {
       logLevel = AV_LOG_FATAL;
-    } else if (std::strcmp(logLevelEnv, "ERROR") == 0) {
+    } else if (logLevelEnv == "ERROR") {
       logLevel = AV_LOG_ERROR;
-    } else if (std::strcmp(logLevelEnv, "WARNING") == 0) {
+    } else if (logLevelEnv == "WARNING") {
       logLevel = AV_LOG_WARNING;
-    } else if (std::strcmp(logLevelEnv, "INFO") == 0) {
+    } else if (logLevelEnv == "INFO") {
       logLevel = AV_LOG_INFO;
-    } else if (std::strcmp(logLevelEnv, "VERBOSE") == 0) {
+    } else if (logLevelEnv == "VERBOSE") {
       logLevel = AV_LOG_VERBOSE;
-    } else if (std::strcmp(logLevelEnv, "DEBUG") == 0) {
+    } else if (logLevelEnv == "DEBUG") {
       logLevel = AV_LOG_DEBUG;
-    } else if (std::strcmp(logLevelEnv, "TRACE") == 0) {
+    } else if (logLevelEnv == "TRACE") {
       logLevel = AV_LOG_TRACE;
     } else {
       TORCH_CHECK(