[openwrt/openwrt] realtek: imagebuilder: add guard around loader generation

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/63c2add66ec7ff01712c8afb8c9ca6923923e68c

commit 63c2add66ec7ff01712c8afb8c9ca6923923e68c
Author: Eric Fahlgren <ericfahlgren at gmail.com>
AuthorDate: Thu Jan 15 13:48:11 2026 -0800

    realtek: imagebuilder: add guard around loader generation
    
    The imagebuilder cannot compile source, so we must guard against
    generation of artifact targets that require this.  Without this
    guard we see an error when building the zyxel,gs1920-24hp-v1 profile.
    
      Create standalone rt-loader, loading uimage from address 0xb40c0000
      mips-openwrt-linux-musl-gcc -fpic -msoft-float -Iinclude -c -o ... src/startup.S
      make[4]: mips-openwrt-linux-musl-gcc: No such file or directory
    
    Signed-off-by: Eric Fahlgren <ericfahlgren at gmail.com>
    Link: https://github.com/openwrt/openwrt/pull/21556
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 target/linux/realtek/image/rtl839x.mk | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/target/linux/realtek/image/rtl839x.mk b/target/linux/realtek/image/rtl839x.mk
index 2e399fd061..c07252eb48 100644
--- a/target/linux/realtek/image/rtl839x.mk
+++ b/target/linux/realtek/image/rtl839x.mk
@@ -100,10 +100,12 @@ TARGET_DEVICES += zyxel_gs1900-48-a1
 
 define Device/zyxel_gs1920-24hp-v1
   FLASH_ADDR := 0xb40c0000
+ifeq ($(IB),)
   ARTIFACTS := loader.bin
   ARTIFACT/loader.bin := \
     rt-loader-standalone | \
     zynsig
+endif
   SOC := rtl8392
   IMAGE_SIZE := 12144k
   DEVICE_VENDOR := Zyxel