Rename ANDROID_SYSTEM_EXT to SYSTEM_EXT_ROOT

SYSTEM_EXT_ROOT is the canonical one, while ANDROID_SYSTEM_EXT is only
used in ART.

Bug: 248037353
Test: TH
Change-Id: I561d8ce74276f74845a1d560b71851bf6e320531
diff --git a/libartbase/base/common_art_test.cc b/libartbase/base/common_art_test.cc
index c55954e..ce02299 100644
--- a/libartbase/base/common_art_test.cc
+++ b/libartbase/base/common_art_test.cc
@@ -340,7 +340,7 @@
   android_system_ext_.append("/system_ext");
   int mkdir_result = mkdir(android_system_ext_.c_str(), 0700);
   ASSERT_EQ(mkdir_result, 0);
-  setenv("ANDROID_SYSTEM_EXT", android_system_ext_.c_str(), 1);
+  setenv("SYSTEM_EXT_ROOT", android_system_ext_.c_str(), 1);
 
   std::string system_ext_framework = android_system_ext_ + "/framework";
   mkdir_result = mkdir(system_ext_framework.c_str(), 0700);
diff --git a/libartbase/base/file_utils.cc b/libartbase/base/file_utils.cc
index acbcd0e..df6c8db 100644
--- a/libartbase/base/file_utils.cc
+++ b/libartbase/base/file_utils.cc
@@ -69,7 +69,7 @@
 static constexpr const char* kClassesDex = "classes.dex";
 static constexpr const char* kAndroidRootEnvVar = "ANDROID_ROOT";
 static constexpr const char* kAndroidRootDefaultPath = "/system";
-static constexpr const char* kAndroidSystemExtRootEnvVar = "ANDROID_SYSTEM_EXT";
+static constexpr const char* kAndroidSystemExtRootEnvVar = "SYSTEM_EXT_ROOT";
 static constexpr const char* kAndroidSystemExtRootDefaultPath = "/system_ext";
 static constexpr const char* kAndroidDataEnvVar = "ANDROID_DATA";
 static constexpr const char* kAndroidDataDefaultPath = "/data";