android build updates

  - update to NDK r20
  - remove a few -I/-L paths we don't need
  - tacking $ndk_api onto -target has Clang set __ANDROID_API__;
    skcms doesn't really care but it's good hygiene
  - harmonize a few minor difference between 32/64-bit builds

Change-Id: I13f1580f16f28948c30e82d07ca97dd65d5f264f
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/225494
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/build/android b/build/android
index 0463652..adb6347 100644
--- a/build/android
+++ b/build/android
@@ -3,16 +3,17 @@
 arch    = arch-arm64
 ndk_api = 24
 
-cc      = $ndk/toolchains/llvm/prebuilt/*/bin/clang   -target $target
-cxx     = $ndk/toolchains/llvm/prebuilt/*/bin/clang++ -target $target
+cc      = $ndk/toolchains/llvm/prebuilt/*/bin/clang   -target $target$ndk_api
+cxx     = $ndk/toolchains/llvm/prebuilt/*/bin/clang++ -target $target$ndk_api
 
-cflags  = -fcolor-diagnostics -Weverything $
-          --sysroot $ndk/sysroot $
-          -I $ndk/sysroot/usr/include/$target
-ldflags = -pie -fuse-ld=gold $
+cflags  = -fcolor-diagnostics -Weverything --sysroot $ndk/sysroot
+
+ldflags = -pie -fuse-ld=lld $
           --sysroot $ndk/platforms/android-$ndk_api/$arch $
-          -B $ndk/toolchains/${target}-4.9/prebuilt/*/$target/bin $
-          -L $ndk/toolchains/${target}-4.9/prebuilt/*/lib/gcc/$target/4.9.x
+          -L $ndk/toolchains/llvm/prebuilt/*/sysroot/usr/lib/$target/$ndk_api $
+          -L $ndk/toolchains/llvm/prebuilt/*/sysroot/usr/lib/$target $
+          -static-libstdc++
+
 out     = out/android$mode
 
 rule run
diff --git a/build/android-arm b/build/android-arm
index d43d14c..92201fb 100644
--- a/build/android-arm
+++ b/build/android-arm
@@ -3,17 +3,18 @@
 arch    = arch-arm
 ndk_api = 24
 
-cc      = $ndk/toolchains/llvm/prebuilt/*/bin/clang   -target $target
-cxx     = $ndk/toolchains/llvm/prebuilt/*/bin/clang++ -target $target
+cc      = $ndk/toolchains/llvm/prebuilt/*/bin/clang   -target $target$ndk_api
+cxx     = $ndk/toolchains/llvm/prebuilt/*/bin/clang++ -target $target$ndk_api
 
-cflags  = -fcolor-diagnostics -Weverything $
-          -march=armv7-a -mthumb $
-          --sysroot $ndk/sysroot $
-          -I $ndk/sysroot/usr/include/$target
-ldflags = -pie -fuse-ld=gold $
+cflags  = -fcolor-diagnostics -Weverything --sysroot $ndk/sysroot $
+          -march=armv7-a -mthumb
+
+ldflags = -pie -fuse-ld=lld $
           --sysroot $ndk/platforms/android-$ndk_api/$arch $
-          -B $ndk/toolchains/${target}-4.9/prebuilt/*/$target/bin $
-          -L $ndk/toolchains/${target}-4.9/prebuilt/*/lib/gcc/$target/4.9.x
+          -L $ndk/toolchains/llvm/prebuilt/*/sysroot/usr/lib/$target/$ndk_api $
+          -L $ndk/toolchains/llvm/prebuilt/*/sysroot/usr/lib/$target $
+          -static-libstdc++
+
 out     = out/android-arm$mode
 
 rule run
@@ -21,7 +22,7 @@
               then $
                   adb push --sync profiles /data/local/tmp >/dev/null; $
                   adb push $in /data/local/tmp/$in >/dev/null; $
-                  adb shell "cd /data/local/tmp; ./$in" > $out; $
+                  adb shell "cd /data/local/tmp; taskset f ./$in" > $out; $
               else touch $out; fi
     description = run $in
 include build/common
diff --git a/infra/bots/gen_tasks.go b/infra/bots/gen_tasks.go
index cdab151..92e5820 100644
--- a/infra/bots/gen_tasks.go
+++ b/infra/bots/gen_tasks.go
@@ -34,7 +34,7 @@
 			&specs.CipdPackage{
 				Name:    "skia/bots/android_ndk_linux",
 				Path:    "ndk",
-				Version: "version:14",
+				Version: "version:15",
 			},
 			&specs.CipdPackage{
 				Name:    "skia/bots/clang_linux",
@@ -56,7 +56,7 @@
 			&specs.CipdPackage{
 				Name:    "skia/bots/android_ndk_darwin",
 				Path:    "ndk",
-				Version: "version:8",
+				Version: "version:9",
 			},
 			// Copied from
 			// https://skia.googlesource.com/skia/+/30a4e3da4bf341d5968b8cdf5bc2260e7f0d4b04/infra/bots/gen_tasks.go#206
diff --git a/infra/bots/tasks.json b/infra/bots/tasks.json
index a84b05d..a61fc7e 100644
--- a/infra/bots/tasks.json
+++ b/infra/bots/tasks.json
@@ -34,7 +34,7 @@
         {
           "name": "skia/bots/android_ndk_linux",
           "path": "ndk",
-          "version": "version:14"
+          "version": "version:15"
         },
         {
           "name": "skia/bots/clang_linux",
@@ -81,7 +81,7 @@
         {
           "name": "skia/bots/android_ndk_darwin",
           "path": "ndk",
-          "version": "version:8"
+          "version": "version:9"
         },
         {
           "name": "infra/tools/mac_toolchain/${platform}",