Fix bash-ism in configure; /bin/sh doesn't handle +=

The script claims to be #!/bin/sh so should not use bash extensions.

Amends 5c40cb0f1a8fad03edb3ef0f97df15e9dd643bdf.

Change-Id: Ib88f528acda0893fd6e96878c49ec5a2cf7ebba7
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/configure b/configure
index cf751ed77f..392ca140c0 100755
--- a/configure
+++ b/configure
@@ -27,7 +27,7 @@ checkTopLevelBuild()
     if [ x"$1" = x"-top-level" ]; then
         CFG_TOPLEVEL=yes
         relpathMangled=`dirname "$relpath"`
-        outpathPrefix+=/..
+        outpathPrefix="$outpathPrefix/.."
     else
         if [ -f ../.qmake.super ]; then
             echo >&2 "ERROR: You cannot configure qtbase separately within a top-level build."