configure.ac: keep posix compat for string tests

'==' and '=' are equivalent in /bin/bash, but POSIX compliant shells do
not understand '==.'

diff --git a/configure.ac b/configure.ac
index 2348dac6ea3f7c7bfe2b6676402d543d319d10d0..1df3a18d501850b54b3e87fb05b8930a81ed4b02 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -566,7 +566,7 @@ AM_CONDITIONAL(HAVE_XZ, [test "$have_xz" = "yes"])
 # ------------------------------------------------------------------------------
 have_lz4=no
 AC_ARG_ENABLE(lz4, AS_HELP_STRING([--enable-lz4], [Enable optional LZ4 support]))
-AS_IF([test "x$enable_lz4" == "xyes"], [
+AS_IF([test "x$enable_lz4" = "xyes"], [
         AC_CHECK_HEADERS(lz4.h,
                [AC_DEFINE(HAVE_LZ4, 1, [Define in LZ4 is available]) have_lz4=yes],
                [AC_MSG_ERROR([*** LZ4 support requested but headers not found])])