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

Reverts llvm/llvm-project#143810 

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

libc/test/src/stdio/fgetc_test.cpp

@@ -33,7 +33,6 @@ public:
     // 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 @@ public:
     // 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"