Driver: Remove major release version detection for RHEL

[tstellar]

Summary

We treat all release of RHEL the same in the driver, so we don't need to
detect the RHEL major release version.

[serge-sans-paille]

LGTM, please reformat the code though.

[tstellar]

Rebase and fix formatting.

clang/include/clang/Driver/Distro.h

enum DistroType {
     DebianWheezy,
     DebianJessie,
     DebianStretch,
     DebianBuster,
     DebianBullseye,
     DebianBookworm,
     DebianTrixie,
     Exherbo,
-    RHEL5,
-    RHEL6,
-    RHEL7,
+    RHEL,
     Fedora,
     Gentoo,
     OpenSUSE,
     UbuntuHardy,
     UbuntuIntrepid,
     UbuntuJaunty,
     UbuntuKarmic,
     UbuntuLucid,
public:
   bool operator<=(const Distro &Other) const {
     return DistroVal <= Other.DistroVal;
   }
 
   /// @}
   /// @name Convenience Predicates
   /// @{
 
-  bool IsRedhat() const {
-    return DistroVal == Fedora || (DistroVal >= RHEL5 && DistroVal <= RHEL7);
-  }
+  bool IsRedhat() const { return DistroVal == Fedora || DistroVal == RHEL; }
 
   bool IsOpenSUSE() const { return DistroVal == OpenSUSE; }
 
   bool IsDebian() const {
     return DistroVal >= DebianLenny && DistroVal <= DebianTrixie;
   }
 
   bool IsUbuntu() const {

clang/lib/Driver/Distro.cpp

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
       VFS.getBufferForFile("/etc/redhat-release");
 
   if (File) {
     StringRef Data = File.get()->getBuffer();
     if (Data.startswith("Fedora release"))
       return Distro::Fedora;
     if (Data.startswith("Red Hat Enterprise Linux") ||
         Data.startswith("CentOS") || Data.startswith("Scientific Linux")) {
-      if (Data.contains("release 7"))
-        return Distro::RHEL7;
-      else if (Data.contains("release 6"))
-        return Distro::RHEL6;
-      else if (Data.contains("release 5"))
-        return Distro::RHEL5;
+      return Distro::RHEL;
     }
     return Distro::UnknownDistro;
   }
 
   // ...for Debian
   File = VFS.getBufferForFile("/etc/debian_version");
   if (File) {
     StringRef Data = File.get()->getBuffer();

clang/unittests/Driver/DistroTest.cpp

CentOS7FileSystem.addFile("/etc/os-release", 0,
                                        "BUG_REPORT_URL=\"https://bugs.centos.org/\"\n"
                                        "\n"
                                        "CENTOS_MANTISBT_PROJECT=\"CentOS-7\"\n"
                                        "CENTOS_MANTISBT_PROJECT_VERSION=\"7\"\n"
                                        "REDHAT_SUPPORT_PRODUCT=\"centos\"\n"
                                        "REDHAT_SUPPORT_PRODUCT_VERSION=\"7\"\n"));
 
   Distro CentOS7{CentOS7FileSystem, llvm::Triple("unknown-pc-linux")};
-  ASSERT_EQ(Distro(Distro::RHEL7), CentOS7);
+  ASSERT_EQ(Distro(Distro::RHEL), CentOS7);
   ASSERT_FALSE(CentOS7.IsUbuntu());
   ASSERT_TRUE(CentOS7.IsRedhat());
   ASSERT_FALSE(CentOS7.IsOpenSUSE());
   ASSERT_FALSE(CentOS7.IsDebian());
   ASSERT_FALSE(CentOS7.IsGentoo());
 }
 
 TEST(DistroTest, DetectOpenSUSE) {