add new matrix mat3x2

Initial function being

glm_mat3x2_make

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

include/cglm/types.h

@@ -55,6 +55,7 @@ typedef float                   vec3[3];
 typedef CGLM_ALIGN_IF(16) float vec4[4];
 typedef vec4                    versor;     /* |x, y, z, w| -> w is the last */
 typedef vec3                    mat3[3];
+typedef vec2                    mat3x2[3];  /* [row (3), col (2)] */
 typedef CGLM_ALIGN_IF(16) vec2  mat2[2];
 typedef vec3                    mat2x3[2];  /* [row (2), col (3)] */
 typedef vec4                    mat2x4[2];  /* [row (2), col (4)] */