Reduce MacOS Risc-V toolchain threads

Author: will-v-pi

packages/macos/riscv/build-riscv-gcc.sh

@@ -14,4 +14,4 @@ export GDB_TARGET_FLAGS_EXTRA
 cd riscv-gnu-toolchain
 ./configure --prefix=$BUILDDIR/$INSTALLDIR --with-arch=rv32ima_zicsr_zifencei_zba_zbb_zbs_zbkb_zca_zcb --with-abi=ilp32 --with-multilib-generator="rv32ima_zicsr_zifencei_zba_zbb_zbs_zbkb_zca_zcb-ilp32--;rv32imac_zicsr_zifencei_zba_zbb_zbs_zbkb-ilp32--"
 # 4 threads, as 8 threads runs out of memory
-gmake -j4
+gmake -j3