[build] Add support for the other MIPS architectures

Change-Id: Id17fdcea3d571c6242bfd8358ff106682e023fec
Reviewed-on: https://chromium-review.googlesource.com/966071
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52015}

tools/toolchain/BUILD.gn

@@ -15,9 +15,79 @@ gcc_toolchain("mips-bundled") {
   ar = "${toolprefix}ar"
   ld = cxx
 
+  # Flag that sets endianness
+  extra_ldflags = "-EB"
+  extra_cppflags = "-EB"
+
   toolchain_args = {
     current_cpu = "mips"
     current_os = "linux"
     is_clang = false
   }
 }
+
+gcc_toolchain("mips64-bundled") {
+  toolprefix = rebase_path("//tools/mips_toolchain/bin/mips-mti-linux-gnu-",
+                           root_build_dir)
+  cc = "${toolprefix}gcc"
+  cxx = "${toolprefix}g++"
+
+  readelf = "${toolprefix}readelf"
+  nm = "${toolprefix}nm"
+  ar = "${toolprefix}ar"
+  ld = cxx
+
+  # Flag that sets endianness and ABI
+  extra_ldflags = "-EB -mabi=64"
+  extra_cppflags = "-EB -mabi=64"
+
+  toolchain_args = {
+    current_cpu = "mips64"
+    current_os = "linux"
+    is_clang = false
+  }
+}
+
+gcc_toolchain("mipsel-bundled") {
+  toolprefix = rebase_path("//tools/mips_toolchain/bin/mips-mti-linux-gnu-",
+                           root_build_dir)
+  cc = "${toolprefix}gcc"
+  cxx = "${toolprefix}g++"
+
+  readelf = "${toolprefix}readelf"
+  nm = "${toolprefix}nm"
+  ar = "${toolprefix}ar"
+  ld = cxx
+
+  # Flag that sets endianness
+  extra_ldflags = "-EL"
+  extra_cppflags = "-EL"
+
+  toolchain_args = {
+    current_cpu = "mipsel"
+    current_os = "linux"
+    is_clang = false
+  }
+}
+
+gcc_toolchain("mips64el-bundled") {
+  toolprefix = rebase_path("//tools/mips_toolchain/bin/mips-mti-linux-gnu-",
+                           root_build_dir)
+  cc = "${toolprefix}gcc"
+  cxx = "${toolprefix}g++"
+
+  readelf = "${toolprefix}readelf"
+  nm = "${toolprefix}nm"
+  ar = "${toolprefix}ar"
+  ld = cxx
+
+  # Flag that sets endianness and ABI
+  extra_ldflags = "-EL -mabi=64"
+  extra_cppflags = "-EL -mabi=64"
+
+  toolchain_args = {
+    current_cpu = "mips64el"
+    current_os = "linux"
+    is_clang = false
+  }
+}