[libc] disable flakey tests

[michaelrj]

Summary

The mprotect test has been failing and causing significant buildbot
noise. Given that this is a simple functions it's more important that
the buildbot errors be useful than having more thorough tests for this
function.

[michaelrj]

remove gettimeofday changes since a proper fix was landed.

libc/test/src/sys/mman/linux/mprotect_test.cpp

TEST(LlvmLibcMProtectTest, NoError) {
   EXPECT_THAT(__llvm_libc::mprotect(addr, alloc_size, PROT_READ | PROT_WRITE),
               Succeeds());
   array[0] = 1;
   EXPECT_EQ(array[0], 1);
 
   EXPECT_THAT(__llvm_libc::munmap(addr, alloc_size), Succeeds());
 }
 
+// This test is disabled currently due to flakeyness. It will be re-enabled once
+// it is less flakey.
+/*
 TEST(LlvmLibcMProtectTest, Error_InvalidWrite) {
   // attempting to write to a read-only protected part of memory should cause a
   // segfault.
   EXPECT_DEATH(
       [] {
         size_t alloc_size = 128;
         void *addr =
             __llvm_libc::mmap(nullptr, alloc_size, PROT_READ | PROT_WRITE,
                               MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
         __llvm_libc::mprotect(addr, alloc_size, PROT_READ);
 
         (reinterpret_cast<char *>(addr))[0] = 'A';
       },
       WITH_SIGNAL(SIGSEGV));
   // Reading from a write only segment may succeed on some platforms, so there's
   // no test to check that.
 }
+*/