crossgcc/Makefile: Allow making toolchains using multiple cores

I looked for a way to pass the 'make crossgcc -j8' on to buildgcc, but
didn't find a way to get that value directly.  MAKEFLAGS turns -j8 into
a jobserver variable.

Instead, this patch allows the number of CPUs to be set on the command
line through a variable instead.

Example: 'make crossgcc BUILDJOBS=8'

Change-Id: I37608cdb4549226cb7ff8c3ff6d9f4773acf6b0b
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: http://review.coreboot.org/10620
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/crossgcc/Makefile

@@ -1,46 +1,46 @@
 all: build-i386 build-x64 build-armv7a build-aarch64 build-mips build-riscv
 
 build-i386:
-	bash ./buildgcc -G -p i386-elf
+	bash ./buildgcc -G -p i386-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 build-x64:
-	bash ./buildgcc -G -p x86_64-elf
+	bash ./buildgcc -G -p x86_64-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 build-armv7a:
-	bash ./buildgcc -G -p armv7a-eabi
+	bash ./buildgcc -G -p armv7a-eabi $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 build-aarch64:
-	bash ./buildgcc -G -p aarch64-elf
+	bash ./buildgcc -G -p aarch64-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 build-mips:
-	bash ./buildgcc -G -p mipsel-elf
+	bash ./buildgcc -G -p mipsel-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 build-riscv:
-	bash ./buildgcc -G -p riscv-elf
+	bash ./buildgcc -G -p riscv-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-i386-without-gdb
 build-i386-without-gdb:
-	bash ./buildgcc -p i386-elf
+	bash ./buildgcc -p i386-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-x64-without-gdb
 build-x64-without-gdb:
-	bash ./buildgcc -p x86_64-elf
+	bash ./buildgcc -p x86_64-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-armv7a-without-gdb
 build-armv7a-without-gdb:
-	bash ./buildgcc -p armv7a-eabi
+	bash ./buildgcc -p armv7a-eabi $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-aarch64-without-gdb
 build-aarch64-without-gdb:
-	bash ./buildgcc -p aarch64-elf
+	bash ./buildgcc -p aarch64-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-mips-without-gdb
 build-mips-without-gdb:
-	bash ./buildgcc -p mipsel-elf
+	bash ./buildgcc -p mipsel-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 .PHONY: build-riscv-without-gdb
 build-riscv-without-gdb:
-	bash ./buildgcc -p riscv-elf
+	bash ./buildgcc -p riscv-elf $(if $(BUILDJOBS),-j $(BUILDJOBS))
 
 clean:
 	rm -rf xgcc