Use binutils objcopy and strip if available

For x86 architectures, binutils objcopy and strip can be used as
such.

For armv7 and aarch64, binutils doesn't recognize the architectures
and refuse to touch the files. For most/everything that objcopy/strip
do, the actual architecture doesn't really matter though. Therefore,
provide a wrapper script and a minimal tool for editing PE executables,
that change the architecture from armv7 and aarch64 to i686 and x86_64
respectively before invoking binutils, and change it back afterwards.

In case the binutils tools are missing, just return a successful result
without doing anything for stripping operations (previously, we had the
<triplet>-strip tool symlinked to /bin/true, so this isn't any worse than
before) and fail for other objcopy operations.

install-wrappers.sh

@@ -12,6 +12,7 @@ PREFIX="$1"
 
 mkdir -p $PREFIX/bin
 cp wrappers/*-wrapper.sh $PREFIX/bin
+cc wrappers/change-pe-arch.c -o $PREFIX/bin/change-pe-arch
 cd $PREFIX/bin
 for arch in $ARCHS; do
     for exec in clang clang++ gcc g++; do
@@ -20,10 +21,10 @@ for arch in $ARCHS; do
     for exec in ar ranlib nm strings; do
         ln -sf llvm-$exec $arch-w64-mingw32-$exec || true
     done
-    for exec in strip; do
-        ln -sf $(which true) $arch-w64-mingw32-$exec
-    done
     for exec in ld objdump windres dlltool; do
         ln -sf $exec-wrapper.sh $arch-w64-mingw32-$exec
     done
+    for exec in objcopy strip; do
+        ln -sf objcopy-wrapper.sh $arch-w64-mingw32-$exec
+    done
 done