path.sh: More thorough gcc/gnat version check

We were checking the shorthand version number, but
the precise version numbers need to match.

Also: when we searched $PATH/gnat-$gccver, we assumed
that the full version would then match, without checking
it, so now it is checked precisely.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/path.sh

@@ -4,27 +4,37 @@
 # fix mismatching gcc/gnat versions on debian trixie/sid
 check_gnat_path()
 {
-	eval `setvars "" gccver gnatver gccdir`
+	eval `setvars "" gccver gccfull gnatver gnatfull gccdir`
 	command -v gcc 1>/dev/null || $err "Command 'gcc' unavailable."
 
 	for _util in gcc gnat; do
 		eval "$_util --version 1>/dev/null 2>/dev/null || continue"
 		eval "${_util}ver=\"`$_util --version 2>/dev/null | head -n1`\""
 		eval "${_util}ver=\"\${${_util}ver##* }\""
+		eval "${_util}full=\"\${$_util}ver\""
 		eval "${_util}ver=\"\${${_util}ver%%.*}\""
 	done
 
 	[ -z "$gccver" ] && $err "Cannot detect host GCC version"
-	[ "$gnatver" = "$gccver" ] && return 0
+	[ "$gnatfull" = "$gccfull" ] && return 0
 
 	gccdir="$(dirname "$(command -v gcc)")"
+	[ -d "$gccdir" ] || $err "gcc PATH dir \"$gccdir\" does not exist."
+
 	for _gnatbin in "$gccdir/gnat-"*; do
 		[ -f "$_gnatbin" ] || continue
 		[ "${_gnatbin#"$gccdir/gnat-"}" = "$gccver" ] || continue
 		gnatver="${_gnatbin#"$gccdir/gnat-"}"
 		break
 	done
-	[ "$gnatver" = "$gccver" ] || $err "GCC/GNAT versions do not match."
+	[ -x "$gccdir/gnat-$gccver" ] || \
+	    $err "$gccdir/gnat-$gccver not executable"
+	gnatfull="`"$gccdir/gnat-$gccver" --version | head -n1`"
+	gnatfull="${gnatfull##* }"
+	[ "${gnatfull%%.*}" = "$gnatver" ] || \
+	    $err "$gccdir/gnat-$gccver v${gnatfull%%.*}; expected v$gnatver"
+
+	[ "$gnatfull" = "$gccfull" ] || $err "GCC/GNAT versions do not match."
 
 	(
 	x_ cd xbmkpath