[PATCH] erofs-utils: build: drop stale liblzma path handling

liblzma now uses PKG_CHECK_MODULES() for path discovery, but a
leftover assignment still rewrote liblzma_LIBS to plain `-llzma`,
dropping pkg-config linker flags such as `-L${prefix}/lib`, which
breaks custom liblzma path discovery.

Remove the redundant logic and drop the obsolete INSTALL.md reference
to --with-liblzma-{incdir,libdir}.

Reported-by: Guo Xuenan <[email protected]>
Fixes: 37ada1b449ae ("erofs-utils: support liblzma auto-detection")
Assisted-by: Codex:GPT-5.5
Signed-off-by: Yifan Zhao <[email protected]>
---
 configure.ac    | 7 -------
 docs/INSTALL.md | 3 ---
 2 files changed, 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index 45b8190..f68bb74 100644
--- a/configure.ac
+++ b/configure.ac
@@ -808,13 +808,6 @@ fi
 
 if test "x${have_liblzma}" = "xyes"; then
   AC_DEFINE([HAVE_LIBLZMA], [1], [Define to 1 if liblzma is enabled.])
-  liblzma_LIBS="-llzma"
-  test -z "${with_liblzma_libdir}" ||
-    liblzma_LIBS="-L${with_liblzma_libdir} $liblzma_LIBS"
-  test -z "${with_liblzma_incdir}" ||
-    liblzma_CFLAGS="-I${with_liblzma_incdir}"
-  AC_SUBST([liblzma_LIBS])
-  AC_SUBST([liblzma_CFLAGS])
 fi
 
 if test "x$have_zlib" = "xyes"; then
diff --git a/docs/INSTALL.md b/docs/INSTALL.md
index 2e818da..0290c2d 100644
--- a/docs/INSTALL.md
+++ b/docs/INSTALL.md
@@ -42,9 +42,6 @@ $ ./configure --enable-lzma
 $ make
 ```
 
-Additionally, you could specify liblzma target paths with
-`--with-liblzma-incdir` and `--with-liblzma-libdir` manually.
-
 ## How to build erofsfuse
 
 It's disabled by default as an experimental feature for now due
-- 
2.47.3