Inaccurate comments in include/cglm/vec3-ext.h

[pm4gh]

The comment for glm_vec3_isnan() "@brief check if all items are NaN (not a number)" is wrong. The one for the same function in vec4-ext.h is better: "@brief check if one of items is NaN (not a number)"

There is a smilar error in glm_vec3_isinf().