Build: Don't put GNU/Linux-specific symbol versions into static liblzma.

It not only makes no sense to put symbol versions into a static library
but it can also cause breakage.

By default Libtool #defines PIC if building a shared library and
doesn't define it for static libraries. This is documented in the
Libtool manual. It can be overriden using --with-pic or --without-pic.
configure.ac detects if --with-pic or --without-pic is used and then
gives an error if neither --disable-shared nor --disable-static was
used at the same time. Thus, in normal situations it works to build
both shared and static library at the same time on GNU/Linux,
only --with-pic or --without-pic requires that only one type of
library is built.

Thanks to John Paul Adrian Glaubitz from Debian for reporting
the problem that occurred on ia64:
https://www.mail-archive.com/xz-devel@tukaani.org/msg00610.html

1 files changed, 4 insertions, 1 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 143a2cbf..5adc3c0a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -477,7 +477,10 @@ elseif(BUILD_SHARED_LIBS AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
     # because it would put symbol versions into the static library which
     # can cause problems. It's clearer if all symver related things are
     # omitted when not building a shared library.
-    target_compile_definitions(liblzma PRIVATE HAVE_SYMBOL_VERSIONS_LINUX)
+    #
+    # NOTE: Set it explicitly to 1 to make it clear that versioning is
+    # done unconditionally in the C files.
+    target_compile_definitions(liblzma PRIVATE HAVE_SYMBOL_VERSIONS_LINUX=1)
     target_link_options(liblzma PRIVATE
         "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/src/liblzma/liblzma_linux.map"
     )