tcg: Introduce tcg_target_call_oarg_reg

Replace the flat array tcg_target_call_oarg_regs[] with
a function call including the TCGCallReturnKind.

Extend the set of registers for ARM to r0-r3 to match the ABI:
https://github.com/ARM-software/abi-aa/blob/main/aapcs32/aapcs32.rst#result-return

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 7b573bd..2f0a952 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -109,12 +109,16 @@
 #endif
 };
 
-static const int tcg_target_call_oarg_regs[] = {
-    TCG_REG_EAX,
-#if TCG_TARGET_REG_BITS == 32
-    TCG_REG_EDX
-#endif
-};
+static TCGReg tcg_target_call_oarg_reg(TCGCallReturnKind kind, int slot)
+{
+    switch (kind) {
+    case TCG_CALL_RET_NORMAL:
+        tcg_debug_assert(slot >= 0 && slot <= 1);
+        return slot ? TCG_REG_EDX : TCG_REG_EAX;
+    default:
+        g_assert_not_reached();
+    }
+}
 
 /* Constants we accept.  */
 #define TCG_CT_CONST_S32 0x100