quote regexps

the parens aren't matched, so the syntax was bogus.

amends 32a3413b13.

Task-number: QTBUG-56580
Change-Id: Ic00ba50844b822c7e4524ae81fbb1bc112a158a9
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>

mkspecs/features/toolchain.prf

@@ -2,10 +2,10 @@
 defineReplace(qtMakeExpand) {
     out = "$$1"
     for(ever) {
-        m = $$replace(out, .*\\$\\(EXPORT_([^)]+)\\).*, \\1)
+        m = $$replace(out, ".*\\$\\(EXPORT_([^)]+)\\).*", \\1)
         equals(m, $$out): \
             return($$out)
-        out = $$replace(out, \\$\\(EXPORT_$$m\\), $$eval($$m))
+        out = $$replace(out, "\\$\\(EXPORT_$$m\\)", $$eval($$m))
     }
 }