https://github.com/gtkwave/gtkwave/pull/455.patch
remove bashism
the dev branch uses meson
--- a/configure
+++ b/configure
@@ -7036,7 +7036,7 @@ $as_echo "$EXZ" >&6; }
 
 LIBXZ_LDADD=
 LIBXZ_CFLAGS=
-if test "X$EXZ" == "Xyes"; then
+if test "X$EXZ" = "Xyes"; then
 	have_liblzma=no
 	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -7126,7 +7126,7 @@ fi
 $as_echo "$FASTTREE" >&6; }
 
 FASTTREE_CFLAGS=
-if test "X$FASTTREE" == "Xno"; then
+if test "X$FASTTREE" = "Xno"; then
 	FASTTREE_CFLAGS='-DWAVE_DISABLE_FAST_TREE'
 fi
 
@@ -7153,7 +7153,7 @@ $as_echo "$EJUDY" >&6; }
 
 LIBJUDY_LDADD=
 LIBJUDY_CFLAGS=
-if test "X$EJUDY" == "Xyes"; then
+if test "X$EJUDY" = "Xyes"; then
 	have_libjudy=no
 	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */