Unify `unset` lval checks with other lvals
tree8a32cf2e01343389f1e19a169670b2a19279f1fb
drwxr-xr-x - .github
-rw-r--r-- 1545 .gitignore
-rw-r--r-- 676 .gitmodules
drwxr-xr-x - CMake
-rw-r--r-- 3172 CMakeLists.txt
-rw-r--r-- 3356 CODE_OF_CONDUCT.md
-rw-r--r-- 3230 CONTRIBUTING.md
-rw-r--r-- 3204 LICENSE.PHP
-rw-r--r-- 2803 LICENSE.ZEND
-rw-r--r-- 2888 README.md
-rw-r--r-- 449 SECURITY.md
-rwxr-xr-x 642 configure
drwxr-xr-x - hphp
drwxr-xr-x - third-party