Revert "Support coverage instrumentation for Linux host"

This reverts commit 358056c058.

Reason for revert: Breaks build_test target in some branches.

Change-Id: I604561033038d4ff15b74caf7b81ff5c8dd9632f

cc/config/x86_linux_host.go

@@ -270,14 +270,6 @@ func (t *toolchainLinuxX8664) YasmFlags() string {
 	return "${config.LinuxX8664YasmFlags}"
 }
 
-func (t *toolchainLinuxX86) profileRuntimeLibrary() string {
-	return "libclang_rt.profile-i386"
-}
-
-func (t *toolchainLinuxX8664) profileRuntimeLibrary() string {
-	return "libclang_rt.profile-x86_64"
-}
-
 func (t *toolchainLinux) AvailableLibraries() []string {
 	return linuxAvailableLibraries
 }