Fix fallout from the merge.

- CI merge issues:
   - The malloc shim libraries are renamed.
   - CMake gets very unhappy if you don't enable the C language and
     tries to link with the C compiler instead of the C++ compiler if
     you do enable it.
   - The Ubuntu packages for QEMU install a `binfmt_misc` activator for
     PowerPC64 little-endian, but set the page size to 4 KiB.  We then
     tried to run the tests (which expect 64 KiB pages) and became very
     confused when `mmap` returned 4 KiB-aligned memory.
 - Test failures:
   - Fix all of the issues UBsan found.
     - Underflow in `pointer_offset` when used to add negative offsets.
     - `CoreAlloc`'s `LocalState` accessed on a null `CoreAlloc` pointer.
     - Out of bounds access in the sizeclass list on attempts to access
       more memory than fits in the VA space.
     -
   - There was an integer overflow in `AddressSpace` that could cause it
     to try to allocate a zero-sized object, get a null pointer, and
     then try to do something with 0 - {size of the real allocation}.
   - The malloc tests weren't setting `errno` to 0 before doing
     calling `malloc`, which should set `errno` on failure, and then
     checking that `errno` was 0.
   - Don't call `PAL::error` on PAL allocation failure, return `nullptr`.
     The PALs were inconsistent about that and the new code expects to be
     able to report address-space exhaustion.
   - The malloc checks can behave differently with 0-sized allocations
     on different platforms but were very fragile about their
     expectations.
   - The malloc test didn't report failure for all of the ways that it
     could fail and so was spuriously passing on some platforms.
   - The perf test for external pointer is currently very slow on
     Windows.  The number of loops have been reduced and a timeout added
     for the Windows CI runs.
   - The logic to capture `errno` across calls was using
     `decltype(errno)`, which on some platforms where `errno` is a macro
     evaluated to `int&` and so they captured a reference rather than
     the value and failed to reset `errno`.
   - The Apple PAL can set `errno` on `notify_using` if it's called with
     memory that was not previously passed to `notify_not_using` but was
     not adequately protected against this and so would sometimes cause
     `malloc` to set `errno` to `EINVAL`.

.github/workflows/main.yml

@@ -50,7 +50,7 @@ jobs:
           - os: ubuntu-latest
             variant: Clang 10 libstdc++ (Build only)
             dependencies: "sudo apt install ninja-build"
-            extra-cmake-flags: "-DCMAKE_CXX_COMPILER=clang++-10 -DCMAKE_CXX_FLAGS=-stdlib=libstdc++"
+            extra-cmake-flags: "-DCMAKE_CXX_COMPILER=clang++-10 -DCMAKE_C_COMPILER=clang-10 -DCMAKE_CXX_FLAGS=-stdlib=libstdc++"
             build-only: yes
       # Don't abort runners if a single one fails
       fail-fast: false
@@ -78,13 +78,11 @@ jobs:
       if: ${{ matrix.self-host }}
       working-directory: ${{github.workspace}}/build
       run: |
-        sudo cp libsnmallocshim.so libsnmallocshim-16mib.so libsnmallocshim-oe.so /usr/local/lib/
+        sudo cp libsnmallocshim.so libsnmallocshim-checks.so /usr/local/lib/
         ninja clean
         LD_PRELOAD=/usr/local/lib/libsnmallocshim.so ninja
         ninja clean
-        LD_PRELOAD=/usr/local/lib/libsnmallocshim-16mib.so ninja
-        ninja clean
-        LD_PRELOAD=/usr/local/lib/libsnmallocshim-oe.so ninja
+        LD_PRELOAD=/usr/local/lib/libsnmallocshim-checks.so ninja
 
   qemu-crossbuild:
     strategy:
@@ -117,6 +115,13 @@ jobs:
         sudo add-apt-repository "deb http://apt.llvm.org/focal/     llvm-toolchain-focal-13  main"
         sudo apt update
         sudo apt install libstdc++-9-dev-${{ matrix.arch.name }}-cross qemu-user ninja-build clang-13 lld-13
+        # The default PowerPC qemu configuration uses the wrong page size.
+        # Wrap it in a script that fixes this.
+        sudo update-binfmts --disable qemu-ppc64le
+        sudo sh -c 'echo ":qemu-ppc64le:M:0:\x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x15\x00:\xff\xff\xff\xff\xff\xff\xff\xfc\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\x00:`pwd`/ppc64.sh:" > /proc/sys/fs/binfmt_misc/register'
+        echo '#!/bin/sh' > ppc64.sh
+        echo '/usr/bin/qemu-ppc64le -p 65536 $@' >> ppc64.sh
+        chmod +x ppc64.sh
     - name: Configure
       run: >
         RTLD_NAME=${{ matrix.arch.rtld }}
@@ -179,6 +184,7 @@ jobs:
     - name: Test
       working-directory: ${{ github.workspace }}/build
       run: ctest -j 2 --interactive-debug-mode 0 --output-on-failure -C ${{ matrix.build-type }}
+      timeout-minutes: 20
 
 
   # Job to run clang-format and report errors