configure: keep the coding style homogenous

Replace tabs with spaces.

Change-Id: Idc72b32450255954fca37af68f873239c186202b

configure

diff --git a/configure b/configure
index a5541bc..c450b2c 100755
--- a/configure
+++ b/configure
@@ -524,7 +524,7 @@
       soft_enable ext_intra_mod
       soft_enable palette_delta_encoding
       soft_enable frame_size
-	  soft_enable segment_globalmv
+      soft_enable segment_globalmv
     fi
 
     # Enable low-bitdepth pixel pipeline by default