Provide <triplet>-<tool> wrappers and links to many llvm tools

Provide wrappers named <triplet>-gcc and <triplet>-g++ as well,
to ease cross compilation with e.g. autotools, to allow just
specifying --host=<triplet>.

Provide wrappers for objdump and ld that provide specific output
that autotools look for.

Provide <triplet>-strip as a symlink to /bin/true, since there is
no strip tool available yet (and llvm-objcopy doesn't support
COFF yet).

wrappers/objdump-wrapper.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+if [ "$1" = "-f" ]; then
+    # libtool can try to run objdump -f and wants to see certain strings in
+    # the output, to accept it being a windows (import) library
+    llvm-readobj $2 | while read -r line; do
+        case $line in
+        File:*)
+            file=$(echo $line | awk '{print $2}')
+            ;;
+        Format:*)
+            format=$(echo $line | awk '{print $2}')
+            case $format in
+            COFF-i386)
+                format=pe-i386
+                ;;
+            COFF-x86-64)
+                format=pe-x86-64
+                ;;
+            COFF-ARM*)
+                # This is wrong; modern COFF armv7 isn't pe-arm-wince, and
+                # arm64 definitely isn't, but libtool wants to see this
+                # string (or some of the others) in order to accept it.
+                format=pe-arm-wince
+                ;;
+            esac
+            echo $file: file format $format
+            ;;
+        esac
+    done
+else
+    llvm-objdump "$@"
+fi