On dash original fails as:
> Creating makefiles for x86-linux-gcc libs
> + write_common_target_config_mk libs-x86-linux-gcc.mk vpx_config.h
> + local CC=x86_64-pc-linux-gnu-gcc -m32
> /tmp/portage/media-libs/libvpx-1.3.0/work/libvpx-v1.3.0/configure: 408: local: -m32: bad variable name

Reported-by: Lars Wendler
Gentoo-bug: https://bugs.gentoo.org/498136
diff --git a/build/make/configure.sh b/build/make/configure.sh
index 8dcb9bb..a38f712 100755
--- a/build/make/configure.sh
+++ b/build/make/configure.sh
@@ -405,8 +405,8 @@ true
 }
 
 write_common_target_config_mk() {
-    local CC=${CC}
-    local CXX=${CXX}
+    local CC="${CC}"
+    local CXX="${CXX}"
     enabled ccache && CC="ccache ${CC}"
     enabled ccache && CXX="ccache ${CXX}"
     print_webm_license $1 "##" ""