fix(cmake): reduce noise in debug build linker flags on Linux

Move optimization-focused linker flags to release builds only:
- --icf=safe: identical code folding for size optimization
- -O2: enable string tail merging optimization
- -z,combreloc: combine relocations for faster loading

Keep debugging-related flags in all builds:
- --compress-debug-sections=zlib: compress debug sections for smaller files
- --gdb-index: faster debug symbol loading in GDB

This reduces verbose linker output and link times in debug builds
while preserving essential debugging functionality.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

cmake/targets/BuildBun.cmake

@@ -993,24 +993,29 @@ if(LINUX)
     --ld-path=${LLD_PROGRAM}
     -fno-pic
     -Wl,-no-pie
-    -Wl,-icf=safe
     -Wl,--as-needed
     -Wl,--gc-sections
     -Wl,-z,stack-size=12800000
     -Wl,--compress-debug-sections=zlib
     -Wl,-z,lazy
     -Wl,-z,norelro
-    # enable string tail merging
-    -Wl,-O2
-    # make debug info faster to load
-    -Wl,--gdb-index
-    -Wl,-z,combreloc
     -Wl,--no-eh-frame-hdr
     -Wl,--sort-section=name
     -Wl,--hash-style=both
     -Wl,--build-id=sha1  # Better for debugging than default
+    # make debug info faster to load
+    -Wl,--gdb-index
     -Wl,-Map=${bun}.linker-map
   )
+
+  if(RELEASE)
+    target_link_options(${bun} PUBLIC
+      -Wl,-icf=safe
+      # enable string tail merging
+      -Wl,-O2
+      -Wl,-z,combreloc
+    )
+  endif()
 endif()
 
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