Fixes a problem when LLVM_DEFINITIONS contains a definition with an `=` in it. add_definitions doesn't seem to parse this type of argument correctly.
Fixes a problem when LLVM_DEFINITIONS contains a definition with an `=` in it.
add_definitions doesn't seem to parse this type of argument correctly.

tuxology/bcc,iovisor/bcc,tuxology/bcc,iovisor/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc,tuxology/bcc,tuxology/bcc,brendangregg/bcc,iovisor/bcc,brendangregg/bcc,iovisor/bcc,iovisor/bcc,brendangregg/bcc