Backport of pcre2-10.48-Fix-allocation-byte-sizing.patch

Backport of pcre2-10.48-Fix-allocation-byte-sizing.patch

Cherry-pick of 8156b3989a82f2ddf9504d8248496e9b124be7f3

Use CU2BYTES for byte sizing in two allocation sites (#909)

Two allocation sites multiplied by PCRE2_CODE_UNIT_WIDTH (the bit width:
8, 16, or 32) where the CU2BYTES(x) byte-count helper is intended. The
result over-allocates by the code-unit byte width: 8x in 8-bit mode, 16x
in 16-bit, 32x in 32-bit. Subsequent memcpy calls already use CU2BYTES
correctly, so no out-of-bounds write occurs; the over-allocation is
leaked until the buffer is freed.

Also guard each site against integer overflow in
sizeof(pcre2_memctl) + CU2BYTES(N + 1) by rejecting N greater than
(PCRE2_SIZE_MAX - sizeof(pcre2_memctl)) / CU2BYTES(1) - 1.

(cherry picked from commit 31ec59526d641b85108c726fe201effc5dca8627)