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..c25148ebdc7ef74b4c92b84389d169bd6cb06a3c 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -295,12 +295,23 @@ config("compiler") {
             "-mips32r2",
             "-Wa,-mips32r2",
           ]
+          if (mips_fpu_mode != "") {
+            cflags += [ "-m$mips_fpu_mode" ]

[wtc, 2015/02/28 00:32:14]

Petar: should we use the -mfp32, -mfp64, -mfpxx flags only when mips_float_api
is "hard"?

If so, I can write a follow-up CL to do that. Thanks.

[petarj, 2015/02/28 02:09:10]

Yes, these flags only make sense if FPU unit is used.

+          }
         } else if (mips_arch_variant == "r1") {
           cflags += [
             "-mips32",
             "-Wa,-mips32",
           ]
         }
+
+        if (mips_dsp_rev == 1) {
+          cflags += [ "-mdsp" ]
+        } else if (mips_dsp_rev == 2) {
+          cflags += [ "-mdspr2" ]
+        }
+
+        cflags += [ "-m${mips_float_abi}-float" ]
       }
     } else if (current_cpu == "mips64el") {
       # Don't set the compiler flags for the WebView build. These will come