external-toolchain: allow override of linux-libc-headers provider

only set PREFERRED_PROVIDER_linux-libc-headers if it is not
already assigned a value.

Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Tested-by: Andrea Galbusera <gizero@gmail.com>
Signed-off-by: Tom Rini <tom_rini@mentor.com>

diff --git a/conf/distro/include/toolchain-external.inc b/conf/distro/include/toolchain-external.inc
index ab50308..12dc454 100644 (file)
--- a/conf/distro/include/toolchain-external.inc
+++ b/conf/distro/include/toolchain-external.inc
@@ -4,7 +4,7 @@ PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc-initial = "external-toolchain-${T
 PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc-intermediate = "external-toolchain-${TOOLCHAIN_BRAND}"
 PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc = "external-toolchain-${TOOLCHAIN_BRAND}"
 PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}g++ = "external-toolchain-${TOOLCHAIN_BRAND}"
-PREFERRED_PROVIDER_linux-libc-headers = "external-toolchain-${TOOLCHAIN_BRAND}"
+PREFERRED_PROVIDER_linux-libc-headers ?= "external-toolchain-${TOOLCHAIN_BRAND}"
 
 TOOLCHAIN_VENDOR ?= "${TARGET_VENDOR}"
 TARGET_VENDOR := "${TOOLCHAIN_VENDOR}"