wasm: include wasi-libc

This allows CGo code to call some libc functions. Additionally, by
putting memset/memmove/memcpy in an archive they're not included anymore
when not necessary, reducing code size for small programs.

.circleci/config.yml

@@ -49,6 +49,18 @@ commands:
           key: llvm-source-9-v0
           paths:
             - llvm-project
+  build-wasi-libc:
+    steps:
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-v0
+      - run:
+          name: "Build wasi-libc"
+          command: make wasi-libc CLANG=$PWD/llvm-build/bin/clang LLVM_AR=$PWD/llvm-build/bin/llvm-ar LLVM_NM=$PWD/llvm-build/bin/llvm-nm
+      - save_cache:
+          key: wasi-libc-sysroot-v0
+          paths:
+            - lib/wasi-libc/sysroot
   test-linux:
     steps:
       - checkout
@@ -62,6 +74,14 @@ commands:
             - go-cache-v2-{{ checksum "go.mod" }}
       - llvm-source-linux
       - run: go install .
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-systemclang-v0
+      - run: make wasi-libc
+      - save_cache:
+          key: wasi-libc-sysroot-systemclang-v0
+          paths:
+            - lib/wasi-libc/sysroot
       - run: go test -v ./cgo ./compileopts ./interp ./transform .
       - run: make gen-device -j4
       - run: make smoketest
@@ -119,6 +139,7 @@ commands:
           paths:
             llvm-build
       - run: make ASSERT=1
+      - build-wasi-libc
       - run:
           name: "Test TinyGo"
           command: make ASSERT=1 test
@@ -176,6 +197,7 @@ commands:
           key: llvm-build-9-linux-v0
           paths:
             llvm-build
+      - build-wasi-libc
       - run:
           name: "Test TinyGo"
           command: make test
@@ -242,6 +264,16 @@ commands:
           key: llvm-build-9-macos-v0
           paths:
             llvm-build
+      - restore_cache:
+          keys:
+            - wasi-libc-sysroot-macos-v0
+      - run:
+          name: "Build wasi-libc"
+          command: make wasi-libc CLANG=$PWD/llvm-build/bin/clang LLVM_AR=$PWD/llvm-build/bin/llvm-ar LLVM_NM=$PWD/llvm-build/bin/llvm-nm
+      - save_cache:
+          key: wasi-libc-sysroot-macos-v0
+          paths:
+            - lib/wasi-libc/sysroot
       - run:
           name: "Test TinyGo"
           command: make test