clang.bbclass: Allow overriding LTO:toolchain-clang

Currently, LTO:toolchain-clang is defined using the immediate assignment
operator (=). This forces the variable to the default value defined in
the class, preventing users from overriding LTO flags for the clang
toolchain via distro configuration or local.conf.

Change the assignment to use the conditional assignment operator (?=).
This ensures that if LTO:toolchain-clang is already set (e.g., in a
distro include file), the custom value is preserved and not overwritten
by the default.

Signed-off-by: mark.yang <mark.yang@lge.com>

0 files changed, 0 insertions, 0 deletions