IES_DECODE_U16 macro: load from 16-bit aligned address

The IES_DECODE_U16 macro loads a 16 bit integer from an arbitrary
address; this can lead to reads from misaligned addresses, and undefined
behavior sanitizer warns, like, e.g., so:

    openair3/NAS/COMMON/IES/ProtocolConfigurationOptions.c:62:5: runtime error: load of misaligned address 0x7f3c24032c01 for type 'uint16_t', which requires 2 byte alignment

To fix this, first use memcpy() to load to a 16-bit aligned address,
then do the actual decoding.

openair3/NAS/COMMON/UTIL/TLVDecoder.h

@@ -62,8 +62,12 @@
 #define IES_DECODE_U8(bUFFER, dECODED, vALUE) \
     DECODE_U8(bUFFER + dECODED, vALUE, dECODED)
 
-#define IES_DECODE_U16(bUFFER, dECODED, vALUE)  \
-    DECODE_U16(bUFFER + dECODED, vALUE, dECODED)
+#define IES_DECODE_U16(bUFFER, dECODED, vALUE)   \
+  do {                                           \
+    uint16_t val;                                \
+    memcpy(&val, bUFFER + dECODED, sizeof(val)); \
+    DECODE_U16(&val, vALUE, dECODED);            \
+  } while (0)
 
 #define IES_DECODE_U24(bUFFER, dECODED, vALUE)  \
     DECODE_U24(bUFFER + dECODED, vALUE, dECODED)