[Buildroot] [git commit branch/2018.11.x] Makefile: unexport 'PLATFORM' and 'OS' environment variables

[Peter Korsgaard]

commit: https://git.buildroot.net/buildroot/commit/?id=bfd008d1325a87cf34740304aa8511c24ed15525
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2018.11.x

Some package builds may fail when environment variables are present with the
same names as make variables in a package. This is a bigger problem for
environment variables with generic names, like 'PLATFORM' and 'OS'.

'PLATFORM' is for example a problem for host-acl.

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire at nokia.com>
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
(cherry picked from commit d3e535a839a893d4721240278fada4652544b60c)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Makefile b/Makefile
index 6379d069d4..c16499808c 100644
--- a/Makefile
+++ b/Makefile
@@ -422,6 +422,8 @@ unexport TERMINFO
 unexport MACHINE
 unexport O
 unexport GCC_COLORS
+unexport PLATFORM
+unexport OS
 
 GNU_HOST_NAME := $(shell support/gnuconfig/config.guess)