`inverseTranspose(mat2)` returns the inverse without transposing

[paulofduarte]

glm::inverseTranspose for mat2 returns the plain inverse, the transpose step is missing. The mat3 and mat4 overloads are correct.

#include <glm/glm.hpp>
#include <glm/gtc/matrix_inverse.hpp>

glm::mat2 const M(1.f, 3.f, 2.f, 4.f);
glm::mat2 const A = glm::inverseTranspose(M);
glm::mat2 const R = glm::transpose(glm::inverse(M));
// A != R, but A == glm::inverse(M)

Cause: in glm/gtc/matrix_inverse.inl, the mat<2, 2, T, Q> overload constructs the same matrix as inverse(mat2) (func_matrix.inl), the two middle cofactors are never swapped.

Not a recent regression: the same implementation appears in the original glm/gtx/inverse_transpose.inl (created 2006) and was carried unchanged through the GTC promotion (cd183ed, 2010). Present on master and in 1.0.3. Configuration-independent (pure arithmetic); observed with clang on macOS/aarch64.

PR to follow with the one-line fix plus a regression test in test/gtc/gtc_matrix_inverse.cpp.