configure: Fix spurious tabs
diff --git a/configure.ac b/configure.ac
index 633816e..d3439d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -121,12 +121,12 @@
 # Check for valgrind
 AS_IF([test "x$enable_tests" = "xno"], [enable_valgrind=no])
 m4_foreach([vgtool], [valgrind_tool_list],
-	[AX_VALGRIND_DFLT(vgtool, [off])])
+    [AX_VALGRIND_DFLT(vgtool, [off])])
 AX_VALGRIND_DFLT([memcheck], [on])
 AX_VALGRIND_CHECK
 AM_EXTRA_RECURSIVE_TARGETS([check-valgrind])
 m4_foreach([vgtool], [valgrind_tool_list],
-	[AM_EXTRA_RECURSIVE_TARGETS([check-valgrind-]vgtool)])
+    [AM_EXTRA_RECURSIVE_TARGETS([check-valgrind-]vgtool)])
 
 # Code coverage
 AX_CODE_COVERAGE