ld-version: Fix awk regex compile failure

The ld-version.sh script fails on some versions of awk with the
following error, resulting in build failures for MIPS:

awk: scripts/ld-version.sh: line 4: regular expression compile failed (missing '(')

This is due to the regular expression ".*)", meant to strip off the
beginning of the ld version string up to the close bracket, however
brackets have a meaning in regular expressions, so lets escape it so
that awk doesn't expect a corresponding open bracket.

Fixes: ccbef16 ("Kbuild, lto: add ld-version and ld-ifversion ...")
Reported-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: James Hogan <[email protected]>
Tested-by: Michael S. Tsirkin <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Tested-by: Sudip Mukherjee <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected] # 4.4.x-
Patchwork: https://patchwork.linux-mips.org/patch/12838/
Signed-off-by: Ralf Baechle <[email protected]>

Author: James Hogan

scripts/ld-version.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/awk -f
 # extract linker version number from stdin and turn into single number
 	{
-	gsub(".*)", "");
+	gsub(".*\\)", "");
 	gsub(".*version ", "");
 	gsub("-.*", "");
 	split($1,a, ".");