Fix unaligned memory accesses as reported by ASan

e.g. runtime error: store to misaligned address 0x7ffec33195e3 for type
'short int', which requires 2 byte alignment

These aren't a problem for x86, but could be a problem for some other CPU
architectures that don't support unaligned access. I didn't use memcpy() to
resolve this (though that would've worked) to make this change endian agnostic.

src/sbbs3/ars.c

@@ -565,8 +565,8 @@ uchar* arstr(ushort* count, const char* str, scfg_t* cfg, uchar* ar_buf)
 				p=strchr(str+i,':');
 				if(p)
 					n+=atoi(p+1);
-				*((short *)(ar+j))=n;
-				j+=2;
+				ar[j++] = n & 0xff;
+				ar[j++] = (n >> 8) & 0xff;
 				while(IS_DIGIT(str[i+1]) || str[i+1]==':') i++;
 				continue;
 			}
@@ -606,16 +606,16 @@ uchar* arstr(ushort* count, const char* str, scfg_t* cfg, uchar* ar_buf)
 				case AR_DLS:
 				case AR_DLK:
 				case AR_DLM:
-					*((short *)(ar+j))=n;
-					j+=sizeof(short);
+					ar[j++] = n & 0xff;
+					ar[j++] = (n >> 8) & 0xff;
 					break;
 				case AR_GROUP:
 				case AR_LIB:
 				case AR_DIR:
 				case AR_SUB:
-					if(n) n--;              /* convert to 0 base */
-					*((short *)(ar+j))=n;
-					j+=2;
+					if(n > 0) n--;              /* convert to 0 base */
+					ar[j++] = n & 0xff;
+					ar[j++] = (n >> 8) & 0xff;
 					break;
 				default:                    /* invalid numeric AR type */
 					j--;
@@ -663,8 +663,8 @@ uchar* arstr(ushort* count, const char* str, scfg_t* cfg, uchar* ar_buf)
 					if(!strnicmp(str+i,cfg->sub[n]->code,strlen(cfg->sub[n]->code)))
 						break;
 				if(n<(uint)cfg->total_subs) {
-					*((short *)(ar+j))=n;
-					j+=2; 
+					ar[j++] = n & 0xff;
+					ar[j++] = (n >> 8) & 0xff;
 				}
 				else        /* Unknown sub-board */
 					j--;
@@ -675,8 +675,8 @@ uchar* arstr(ushort* count, const char* str, scfg_t* cfg, uchar* ar_buf)
 					if(!strnicmp(str+i,cfg->dir[n]->code,strlen(cfg->dir[n]->code)))
 						break;
 				if(n<(uint)cfg->total_dirs) {
-					*((short *)(ar+j))=n;
-					j+=2; 
+					ar[j++] = n & 0xff;
+					ar[j++] = (n >> 8) & 0xff;
 				}
 				else        /* Unknown directory */
 					j--;