ltmain: Pass through -fno-lto and -ffixed=*

Reported: https://lists.gnu.org/archive/html/libtool-patches/2026-09/msg00000.html

* build-aux/ltmain.in: Pass through -fno-lto and -ffixed=*.
* NEWS: Update.

NEWS

diff --git a/NEWS b/NEWS
index 827c97a..b702d93 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** New features:
+
+  - Pass through -fno-lto and -ffixed=* to disable link-time optimization
+    and reserve registers.
+
 ** Changes in supported systems or compilers:
 
   - Support AOCC Fortran compiler 'aof'.

build-aux/ltmain.in

diff --git a/build-aux/ltmain.in b/build-aux/ltmain.in
index af2f756..0cf5aaf 100644
--- a/build-aux/ltmain.in
+++ b/build-aux/ltmain.in
@@ -5666,6 +5666,8 @@
       # --sysroot=*          for sysroot support
       # --target=*           for target architecture support
       # -O*, -g*, -flto*, -fwhopr*, -fuse-linker-plugin GCC link-time optimization
+      # -fno-lto             disable link-time optimization
+      # -ffixed=*            reserve registers
       # -specs=*             GCC specs files
       # -stdlib=*            select c++ std lib with clang
       # -fdiagnostics-color* simply affects output
@@ -5687,6 +5689,7 @@
       -64|-mips[0-9]|-r[0-9][0-9]*|-xarch=*|-xtarget=*|+DA*|+DD*|-q*|-m*| \
       -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*|--sysroot=*|--target=*| \
       -O*|-g*|-flto*|-fwhopr*|-fuse-linker-plugin|-fstack-protector*|-no-canonical-prefixes| \
+      -fno-lto|-ffixed=*| \
       -stdlib=*|-resource-dir=*|-rtlib=*|--unwindlib=*| \
       -specs=*|-fsanitize=*|-fno-sanitize*|-shared-libsan|-static-libsan| \
       -ffile-prefix-map=*|-fdebug-prefix-map=*|-fmacro-prefix-map=*|-fprofile-prefix-map=*| \