scripts: bundle-libraries.sh: fix broken SDK compiler

Recent versions (> 5.33) of `file` report liblto_plugin.so as
executable:

 $ file liblto_plugin.so
 liblto_plugin.so.0.0.0: ELF 64-bit LSB pie executable ...

Which then leads to improper packaging of the plugin, resulting in the
broken compiler:

 configure: checking whether the C compiler works
 mips-openwrt-linux-musl/bin/ld: liblto_plugin.so: error loading plugin: liblto_plugin.so: invalid ELF header

As the LTO compiler plugin library is incorrectly packaged as SDK
executable:

 $ head -1 ~/staging_dir/toolchain...libexec/gcc/.../liblto_plugin.so
 #!/usr/bin/env bash

Fix this by filtering out shared libraries from the patching.

Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1296868
Acked-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

scripts/bundle-libraries.sh

@@ -125,6 +125,23 @@ _patch_glibc() {
 	fi
 }
 
+should_be_patched() {
+	local bin="$1"
+
+	[ -x "$bin" ] || return 1
+
+	case "$bin" in
+		*.so|*.so.[0-9]*)
+			return 1
+		;;
+		*)
+			file "$bin" | grep -sqE "ELF.*(executable|interpreter)" && return 0
+		;;
+	esac
+
+	return 1
+}
+
 for LDD in ${PATH//://ldd }/ldd; do
 	"$LDD" --version >/dev/null 2>/dev/null && break
 	LDD=""
@@ -150,7 +167,7 @@ for BIN in "$@"; do
 
 	LDSO=""
 
-	[ -n "$LDD" ] && [ -x "$BIN" ] && file "$BIN" | grep -sqE "ELF.*(executable|interpreter)" && {
+	[ -n "$LDD" ] && should_be_patched "$BIN" && {
 		for token in $("$LDD" "$BIN" 2>/dev/null); do
 			case "$token" in */*.so*)
 				dest="$DIR/lib/${token##*/}"