wasm: update wasi-libc dependency

Several updates are necessary for LLVM 11 support, so simply update to
the latest commit.

.circleci/config.yml

@@ -60,12 +60,12 @@ commands:
     steps:
       - restore_cache:
           keys:
-            - wasi-libc-sysroot-v2
+            - wasi-libc-sysroot-v3
       - run:
           name: "Build wasi-libc"
           command: make wasi-libc
       - save_cache:
-          key: wasi-libc-sysroot-v2
+          key: wasi-libc-sysroot-v3
           paths:
             - lib/wasi-libc/sysroot
   test-linux:
@@ -87,10 +87,10 @@ commands:
       - run: go install -tags=llvm<<parameters.llvm>> .
       - restore_cache:
           keys:
-            - wasi-libc-sysroot-systemclang-v1
+            - wasi-libc-sysroot-systemclang-v2
       - run: make wasi-libc
       - save_cache:
-          key: wasi-libc-sysroot-systemclang-v1
+          key: wasi-libc-sysroot-systemclang-v2
           paths:
             - lib/wasi-libc/sysroot
       - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./interp ./transform .
@@ -283,12 +283,12 @@ commands:
             llvm-build
       - restore_cache:
           keys:
-            - wasi-libc-sysroot-macos-v1
+            - wasi-libc-sysroot-macos-v2
       - run:
           name: "Build wasi-libc"
           command: make wasi-libc
       - save_cache:
-          key: wasi-libc-sysroot-macos-v1
+          key: wasi-libc-sysroot-macos-v2
           paths:
             - lib/wasi-libc/sysroot
       - run:

azure-pipelines.yml

@@ -47,7 +47,7 @@ jobs:
     - task: CacheBeta@0
       displayName: Cache wasi-libc sysroot
       inputs:
-        key: wasi-libc-sysroot-v2
+        key: wasi-libc-sysroot-v3
         path: lib/wasi-libc/sysroot
     - task: Bash@3
       displayName: Build wasi-libc

lib/wasi-libc

@@ -1 +1 @@
-Subproject commit a280fead2ae71b9a230d3b48c1f95867431888e4
+Subproject commit 215adc8ac9f91eb055311acc72683fd2eb1ae15a