builder: msys2: fix links to host binaries

Factor out non-environment code from host_env()/target_env() into
host_env_base()/target_env_base(). Such as that for creating symlinks to
root, link host binaries to the target root, as well as calling the
hook.

Call the _base() functions from the msys2 overrides so that symlinks are
created properly, remove redundant symlink code.

tools/builder/core.sh

@@ -13,7 +13,7 @@ export PERL_MAKE="${PERL_MAKE:-make}"
 
 BUILD_ENV=$BUILD_ENV$(cat <<EOF
 
-export BUILD_ROOT="\$BUILD_ROOT"
+export BUILD_ROOT="\${BUILD_ROOT:-$BUILD_ROOT}"
 
 export CC="\${CC:-gcc}"
 export CXX="\${CXX:-g++}"

tools/builder/mingw.sh

@@ -71,9 +71,13 @@ fi
 
 both_dists=$(list_remove_duplicates $both_dists)
 
-host_env() {
+host_env_base() {
     rm -f "$BUILD_ROOT/root"
     ln -sf "$BUILD_ROOT/host" "$BUILD_ROOT/root"
+    host_env_hook 2>/dev/null || :
+}
+
+host_env() {
     if [ -z "$OCC" ]; then
         cat <<EOF
 OCC="\$CC"
@@ -110,13 +114,28 @@ REQUIRED_CMAKE_ARGS="\$(puts "\$REQUIRED_CMAKE_ARGS" | sed 's/-DCMAKE_TOOLCHAIN_
 EOF
     fi
 
-    host_env_hook 2>/dev/null || :
+    host_env_base 2>/dev/null || :
 }
 
-target_env() {
+target_env_base() {
     rm -f "$BUILD_ROOT/root"
     ln -sf "$BUILD_ROOT/target" "$BUILD_ROOT/root"
 
+    # make links to executables in the target as well
+    IFS=$NL
+    for exe in $(find "$BUILD_ROOT/host/bin" -maxdepth 1 -type f); do
+        IFS=$OIFS
+        basename=${exe##*/}
+        if ! path_exists "$BUILD_ROOT/target/bin/$basename"; then
+            ln -s "$exe" "$BUILD_ROOT/target/bin/$basename";
+        fi
+    done
+    IFS=$OIFS
+
+    target_env_hook 2>/dev/null || :
+}
+
+target_env() {
     if [ -n "$OCC" ]; then
         cat <<EOF
 export CC="\$OCC"
@@ -140,18 +159,7 @@ $BUILD_ENV
 EOF
     fi
 
-    # make links to executables in the target as well
-    IFS=$NL
-    for exe in $(find "$BUILD_ROOT/host/bin" -maxdepth 1 -type f); do
-        IFS=$OIFS
-        basename=${exe##*/}
-        if ! path_exists "$BUILD_ROOT/target/bin/$basename"; then
-            ln -s "$exe" "$BUILD_ROOT/target/bin/$basename";
-        fi
-    done
-    IFS=$OIFS
-
-    target_env_hook 2>/dev/null || :
+    target_env_base 2>/dev/null || :
 }
 
 # replace install artifact paths with absolute paths into host and target trees

tools/win/msys2-builder

@@ -107,8 +107,6 @@ DIST_TAR_ARGS="
 . "${0%/*}/../builder/mingw.sh"
 
 host_env() {
-    ln -sf "$BUILD_ROOT/host" "$BUILD_ROOT/root"
-
     cat <<EOF
 unset MSYSTEM_PREFIX MSYSTEM_CARCH MSYSTEM_CHOST MINGW_CHOST MINGW_PREFIX MINGW_PACKAGE_PREFIX CONFIG_SITE ACLOCAL_PATH PKG_CONFIG_PATH
 
@@ -120,11 +118,10 @@ $BUILD_ENV
 EOF
 
     cd "$OPWD"
+    host_env_base 2>/dev/null || :
 }
 
 target_env() {
-    ln -sf "$BUILD_ROOT/target" "$BUILD_ROOT/root"
-
     cat <<EOF
 unset MSYSTEM_PREFIX MSYSTEM_CARCH MSYSTEM_CHOST MINGW_CHOST MINGW_PREFIX MINGW_PACKAGE_PREFIX CONFIG_SITE ACLOCAL_PATH PKG_CONFIG_PATH
 
@@ -136,6 +133,7 @@ $BUILD_ENV
 EOF
 
     cd "$OPWD"
+    target_env_base 2>/dev/null || :
 }
 
 table_line_append DIST_PRE_BUILD c2man ":; \