I built cogl package for both qemuarm and beagleboard machines without any issues. See the build configurations below. Also, according to ARM documentation for the CLZ instruction:

"This ARM instruction is available in ARMv5T and above.
This 32-bit Thumb instruction is available in ARMv6T2 and above.
There is no 16-bit Thumb version of this instruction."

Can you please provide more info about the config used to replicate the issue?

Configs I used:
[1]
Build Configuration:
BB_VERSION        = "1.17.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-12.04"
TARGET_SYS        = "arm-poky-linux-gnueabi"
MACHINE           = "qemuarm"
DISTRO            = "poky"
DISTRO_VERSION    = "1.3+snapshot-20121214"
TUNE_FEATURES     = "armv5 thumb dsp"
TARGET_FPU        = "soft"
meta
meta-yocto
meta-yocto-bsp    = "master:da598d4f0fcf6faa62055084a51d70d735399d33"

[2]
Build Configuration:
BB_VERSION        = "1.17.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-12.04"
TARGET_SYS        = "arm-poky-linux-gnueabi"
MACHINE           = "beagleboard"
DISTRO            = "poky"
DISTRO_VERSION    = "1.3+snapshot-20121214"
TUNE_FEATURES     = "armv7a vfp neon" 
TARGET_FPU        = "vfp-neon"
meta
meta-yocto
meta-yocto-bsp    = "master:da598d4f0fcf6faa62055084a51d70d735399d33"

This bug came from a list of issues that Martin Jansa Pointed out when building arm with world.  It may have been he was building distro-less or with his distro, please refer to the "State of bitbake World" email on the oe-core list and maybe reply to Martin for more info.

No idea since when, but now it seems to be building correctly on distro-less qemuarm.