Add the mips_dsp_rev build variable.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 8cb4088b1695e821e905963147ea100eab7481dc..3854289e792a48d53e2230f94bbaa8c2d8c55362 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -301,6 +301,28 @@ config("compiler") {
             "-Wa,-mips32",
           ]
         }
+
+        if (mips_dsp_rev == 1) {
+          cflags += [ "-mdsp" ]
+        } else if (mips_dsp_rev == 2) {
+          cflags += [ "-mdspr2" ]
+        }
+
+        if (mips_float_abi == "hard") {
+          cflags += [ "-mhard-float" ]
+        } else {
+          cflags += [ "-msoft-float" ]
+        }
+
+        if (mips_arch_variant == "r2") {
+          if (mips_fpu_mode == "fp32") {
+            cflags += [ "-mfp32" ]
+          } else if (mips_fpu_mode == "fp64") {
+            cflags += [ "-mfp64" ]
+          } else if (mips_fpu_mode == "fpxx") {
+            cflags += [ "-mfpxx" ]
+          }
+        }
       }
     } else if (current_cpu == "mips64el") {
       # Don't set the compiler flags for the WebView build. These will come