Revert "[libc] Fix stdio tests after #143802" (#143824)

Reverts #143810 

This PR breaks our buildbot:
https://lab.llvm.org/buildbot/#/builders/10/builds/7159 revert to
unblock downstream merge.

Author: Kewen12

libc/docs/configure.rst

@@ -29,7 +29,7 @@ to learn about the defaults for your platform and target.
     - ``LIBC_CONF_ENABLE_STRONG_STACK_PROTECTOR``: Enable -fstack-protector-strong to defend against stack smashing attack.
     - ``LIBC_CONF_KEEP_FRAME_POINTER``: Keep frame pointer in functions for better debugging experience.
 * **"errno" options**
-    - ``LIBC_CONF_ERRNO_MODE``: The implementation used for errno, acceptable values are LIBC_ERRNO_MODE_DEFAULT, LIBC_ERRNO_MODE_UNDEFINED, LIBC_ERRNO_MODE_THREAD_LOCAL, LIBC_ERRNO_MODE_SHARED, LIBC_ERRNO_MODE_EXTERNAL, LIBC_ERRNO_MODE_SYSTEM, and LIBC_ERRNO_MODE_SYSTEM_INLINE.
+    - ``LIBC_CONF_ERRNO_MODE``: The implementation used for errno, acceptable values are LIBC_ERRNO_MODE_DEFAULT, LIBC_ERRNO_MODE_UNDEFINED, LIBC_ERRNO_MODE_THREAD_LOCAL, LIBC_ERRNO_MODE_SHARED, LIBC_ERRNO_MODE_EXTERNAL, and LIBC_ERRNO_MODE_SYSTEM.
 * **"general" options**
     - ``LIBC_ADD_NULL_CHECKS``: Add nullptr checks in the library's implementations to some functions for which passing nullptr is undefined behavior.
 * **"math" options**

libc/test/src/stdio/fgetc_test.cpp

@@ -33,7 +33,6 @@ class LlvmLibcGetcTest : public LIBC_NAMESPACE::testing::ErrnoCheckingTest {
     // This is an error and not a real EOF.
     ASSERT_EQ(LIBC_NAMESPACE::feof(file), 0);
     ASSERT_NE(LIBC_NAMESPACE::ferror(file), 0);
-    ASSERT_ERRNO_FAILURE();
 
     ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
 

libc/test/src/stdio/fgetc_unlocked_test.cpp

@@ -36,7 +36,6 @@ class LlvmLibcGetcTest : public LIBC_NAMESPACE::testing::ErrnoCheckingTest {
     // This is an error and not a real EOF.
     ASSERT_EQ(LIBC_NAMESPACE::feof(file), 0);
     ASSERT_NE(LIBC_NAMESPACE::ferror(file), 0);
-    ASSERT_ERRNO_FAILURE();
 
     ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
 

libc/test/src/stdio/fgets_test.cpp

@@ -36,7 +36,6 @@ TEST_F(LlvmLibcFgetsTest, WriteAndReadCharacters) {
   // This is an error and not a real EOF.
   ASSERT_EQ(LIBC_NAMESPACE::feof(file), 0);
   ASSERT_NE(LIBC_NAMESPACE::ferror(file), 0);
-  ASSERT_ERRNO_FAILURE();
 
   ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
 

libc/test/src/stdio/setvbuf_test.cpp

@@ -11,7 +11,6 @@
 #include "src/stdio/fread.h"
 #include "src/stdio/fwrite.h"
 #include "src/stdio/setvbuf.h"
-#include "test/UnitTest/ErrnoCheckingTest.h"
 #include "test/UnitTest/Test.h"
 
 #include "hdr/stdio_macros.h"