After an upgrade from mesa-17.3.0-2.parabola1-i686 to mesa-17.3.1-2.parabola1-i686 compton does not start. Error message when starting compton:
glx_init(): No GLX extension.

Manually downgrading to mesa-17.3.0-2.parabola1-i686 again solves the problem.

Some info on my system:

$ cat /proc/version
Linux version 4.14.10-gnu-1 (builduser@ebrasca-parabola) (gcc version 7.2.0 (GCC)) #1 SMP PREEMPT Thu Jan 4 03:28:51 UTC 2018

$ lspci | grep -e VGA -e 3D
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)

$ lscpu
Architecture: i686
CPU op-mode(s): 32-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0,1
Thread(s) per core: 1
Core(s) per socket: 2
Socket(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 14
Model name: Genuine Intel(R) CPU 1300 @ 1.66GHz
Stepping: 8
CPU MHz: 1000.000
CPU max MHz: 1666.0000
CPU min MHz: 1000.0000
BogoMIPS: 3326.54
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 2048K
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc bts cpuid aperfmperf pni monitor vmx est tm2 xtpr pdcm dtherm