add new matrix mat4x2

Initial function being

glm_mat4x2_make

Signed-off-by: Vincent Davis Jr <vince@underview.tech>

include/cglm/types.h

@@ -61,6 +61,7 @@ typedef CGLM_ALIGN_IF(16) vec2  mat2[2];
 typedef vec3                    mat2x3[2];  /* [col (2), row (3)] */
 typedef vec4                    mat2x4[2];  /* [col (2), row (4)] */
 typedef CGLM_ALIGN_MAT    vec4  mat4[4];
+typedef vec2                    mat4x2[4];  /* [col (4), row (2)] */
 
 /*
   Important: cglm stores quaternion as [x, y, z, w] in memory since v0.4.0