strfind: assure re-check is done on mismatch after initial match + add tests

src/string.asm

@@ -192,6 +192,17 @@ strfind:
 
 		.noMatch:
 		; not gonna figure out here if there was an existing match already. just XOR r10b,r10b and load original pointer to what[] to rsi
+		; EDIT: actually yes I am. strfind("gidgiddy", "giddy", 0); [gid]giddy<>[gid]dy is a match but then gid[g]iddy<>gid[d]y is not while it should check gid[g]iddy<>[g]iddy
+		test	r10b, r10b
+		jz	.continueLoop
+		mov	rsi, r11
+		mov	r9b, byte [rsi]
+		cmp	byte [rdi], r9b
+		jne	.itReallyWasNoMatchAfterAll
+		mov	r8, rcx
+		inc	rsi
+		jmp	.continueLoop
+		.itReallyWasNoMatchAfterAll:
 		xor	r10b, r10b
 		mov	rsi, r11