python3-matplotlib: Disable LTO for clang/riscv
LTO fails to link on RV32/RV64
| Hard-float 'd' ABI can't be used for a target that doesn't support the D instruction set extension (
ignoring target-abi)
| riscv64-yoe-linux-ld.lld: error: lto.tmp: cannot link object files with different floating-point ABI
Signed-off-by: Khem Raj <raj.khem@gmail.com>