Merge remote-tracking branch 'origin/issue-955' into integration_2025_w31 (!3545)

Fix overflow when negating minimum int16_t value in precoding

This closes #955

It prevents undefined behavior caused by the minimum int16_t value
(-32768) in two's complement representation. Because possible negation
by multiplying with -1 during precoding cause an overflows since +32768
cannot be represented in 16-bit signed integers and end up again in
-32768 because of overflow, here reveald by using the SIMD functions.

Workaround we use a slightly smaller number than 1 in Q15 Format to
prevent this error. Q15 representation of (integer value -32767) -1 +
2^-15 = -0.999969482421875

openair1/PHY/TOOLS/tools_defs.h

@@ -163,7 +163,7 @@ extern "C" {
   __attribute__((always_inline)) inline c16_t c16conj(const c16_t a) {
     return (c16_t) {
       .r =  a.r,
-      .i = (int16_t)-a.i
+      .i =  (int16_t)-a.i
     };
   }