liblzma: Rename the private API header lzma/lzma.h to lzma/lzma12.h.

It can be confusing that two header files have the same name.
The public API file is still lzma.h.

src/liblzma/api/Makefile.am

@@ -17,7 +17,7 @@ nobase_include_HEADERS = \
 	lzma/hardware.h \
 	lzma/index.h \
 	lzma/index_hash.h \
-	lzma/lzma.h \
+	lzma/lzma12.h \
 	lzma/stream_flags.h \
 	lzma/version.h \
 	lzma/vli.h

src/liblzma/api/lzma.h

@@ -286,7 +286,7 @@ extern "C" {
 #include "lzma/filter.h"
 #include "lzma/bcj.h"
 #include "lzma/delta.h"
-#include "lzma/lzma.h"
+#include "lzma/lzma12.h"
 
 /* Container formats */
 #include "lzma/container.h"

src/liblzma/api/lzma/lzma12.h

@@ -1,5 +1,5 @@
 /**
- * \file        lzma/lzma.h
+ * \file        lzma/lzma12.h
  * \brief       LZMA1 and LZMA2 filters
  */