On RHEL and CentOS, don't use libc++ since we are using the devtoolset-7 which has a newer g++

hipamd/bin/hipcc

@@ -125,9 +125,7 @@ if ($HIP_PLATFORM eq "hcc") {
 
     # Force -stdlib=libc++ on UB14.04
     $HOST_OSVER= `cat /etc/os-release | grep "^VERSION_ID\=" | cut -d= -f2 | tr -d '\n'`;
-    if (($HOST_OSNAME eq "ubuntu" and $HOST_OSVER eq "\"14.04\"")
-         or ($HOST_OSNAME eq "\"centos\"" and $HOST_OSVER eq "\"7\"")
-         or ($HOST_OSNAME eq "\"rhel\"" and $HOST_OSVER eq "\"7.4\"")) {
+    if ($HOST_OSNAME eq "ubuntu" and $HOST_OSVER eq "\"14.04\"") {
         $HIPCXXFLAGS .= " -stdlib=libc++";
         $setStdLib = 1;
     }