Error when I compile 'hello-world' example from Contiki

I have installed the Contiki OS sources, and the ARM GCC compiler by doing brew install arm-none-eabi-gcc. However, when I try to run the hello world example in Contiki's example folder using the command make TARGET=srf06-cc26xx BOARD=sensortag/cc2650 hello-world.bin CPU_FAMILY=cc26xx, I get the following error message:

  CC        ../../cpu/cc26xx-cc13xx/lib/cc26xxware/startup_files/ccfg.c
arm-none-eabi-gcc: error: unrecognized -march target: core2
arm-none-eabi-gcc: note: valid arguments are: armv4 armv4t armv5t armv5te armv5tej armv6 armv6j armv6k armv6z armv6kz armv6zk armv6t2 armv6-m armv6s-m armv7 armv7-a armv7ve armv7-r armv7-m armv7e-m armv8-a armv8.1-a armv8.2-a armv8.3-a armv8.4-a armv8.5-a armv8-m.base armv8-m.main armv8-r iwmmxt iwmmxt2
arm-none-eabi-gcc: error: missing argument to '-march='
arm-none-eabi-gcc: error: unrecognized command line option '-mssse3'
make: *** [obj_srf06-cc26xx/ccfg.o] Error 1

I triple-checked that the ARM GCC compiler is accessible from the terminal by doing arm-none-eabi-gcc --version, and I can see that it is properly installed:

arm-none-eabi-gcc (GNU Tools for Arm Embedded Processors 9-2019-q4-major) 9.2.1 20191025 (release) [ARM/arm-9-branch revision 277599]
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

So I am really not sure what might be wrong here. Can anyone help?

My operating system is macOS Mojave Version 10.14.6.

UPDATE: The makefile is given in the example folder (from contiki):

CONTIKI_PROJECT = hello-world
all: $(CONTIKI_PROJECT)

CONTIKI = ../..
include $(CONTIKI)/Makefile.include

UPDATE 2: By adding V=1 in the command, my output is:

arm-none-eabi-gcc -march=core2 -mtune=haswell -mssse3 -ftree-vectorize
 -fPIC -fPIE -fstack-protector-strong -O2 -pipe -DCONTIKI=1 
-DCONTIKI_TARGET_SRF06_CC26XX=1 -DNETSTACK_CONF_WITH_IPV6=1 
-DUIP_CONF_IPV6_RPL=1 -DBOARD_SENSORTAG=1 -DBACKDOOR_IOID=0x00000000 
-I../../cpu/cc26xx-cc13xx/lib/cc26xxware -I../../cpu/cc26xx-cc13xx
/lib/cc26xxware/driverlib -I../../cpu/cc26xx-cc13xx/lib/cc26xxware/inc 
-mcpu=cortex-m3 -mthumb -mlittle-endian -ffunction-sections -fdata-sections
 -fshort-enums -fomit-frame-pointer -fno-strict-aliasing -Wall -std=c99 -O2
  -I. -I../../platform/srf06-cc26xx/. -I../../platform/srf06-cc26xx
/sensortag/cc2650 -I../../platform/srf06-cc26xx/sensortag -I../../platform
/srf06-cc26xx/common -I../../cpu/cc26xx-cc13xx/. -I../../cpu/cc26xx-cc13xx/dev 
-I../../cpu/cc26xx-cc13xx/rf-core -I../../cpu/cc26xx-cc13xx/rf-core/api -I../../cpu/cc26xx-cc13xx/lib/cc26xxware/startup_files -I../..
/cpu/cc26xx-cc13xx/../arm/common/dbg-io -I../../core/dev -I../../core/lib -I../../core/net -I../../core/net/llsec -I../../core/net/mac -I../..
/core/net/rime -I../../core/net/rpl -I../../core/sys -I../../core/cfs 
-I../../core/ctk -I../../core/lib/ctk -I../../core/loader -I../../core/. -I../../core/sys -I../../core/dev -I../../core/lib -I../../core/net/ipv6 -I../../core/net/ip -I../../core/net/rpl -I../../cpu/cc26xx-cc13xx
/lib/cc26xxware/driverlib -I../../core/net -I../../core/net/mac -I../..
/core/net/mac/contikimac -I../../core/net/llsec -I../../platform/srf06-
cc26xx/ -I../.. -DCONTIKI_VERSION_STRING=\"Contiki-3.x-3345-g32b5b17\" 
-include "contiki-conf.h" -c ../../cpu/cc26xx-cc13xx/lib/cc26xxware
/startup_files/ccfg.c -o obj_srf06-cc26xx/ccfg.o

UPDATE 3: If I do unset CFLAGS, I get a new error message:

/usr/local/Cellar/arm-none-eabi-gcc/9-2019-q4-major/gcc/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: hello-world.elf section `.interp' will not fit in region `FLASH_CCFG'
/usr/local/Cellar/arm-none-eabi-gcc/9-2019-q4-major/gcc/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: region `FLASH_CCFG' overflowed by 9120 bytes
/usr/local/Cellar/arm-none-eabi-gcc/9-2019-q4-major/gcc/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: warning: cannot find entry symbol ad_strip_dylibs; defaulting to 0000000000000000
collect2: error: ld returned 1 exit status
make: *** [hello-world.elf] Error 1
rm obj_srf06-cc26xx/startup_gcc.o hello-world.co obj_srf06-cc26xx/fault-handlers.o

Here's a consolidation of @kfx's solution (which worked like a charm):

1. unset CFLAGS
2. unset LDFLAGS
3. make clean

This is because there may be some other flags which you accidentally set previously, so you have to unset them in order for the compilation to work.