build!: check boolean flags are not empty

For numeric flags, there is a check for the value to be set. Do the same
for boolean flags. This avoids issues where a flag is defined but
without a value, leading to potential unexpected behaviors.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Ib00da2784339471058887e93434d96ccba2aebb2
1 file changed