build.sh: Unset EXT_MODULES for GKI kernel in mixed build

Ensure EXT_MODULES isn't inherited from environment by explicitly
unsetting EXT_MODULES when compiling the GKI kernel in mixed build.
External vendor modules should be compiled against the vendor kernel,
which would have vendor symbols available.

Bug: 178469391
Change-Id: Iffb0e396bf4b7f2b51b7aaed5b165c6d6f0e5d04
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
1 file changed