transferred implementation inside xxhash.h

instead of xxhash.c .

This seems preferable for some build systems,
which don't like the `#include "xxhash.c"` statement
when inlining xxhash, as reported by @pdillinger .

Note that `xxhash.c` still exists,
it just includes the implementation and instantiates it.

Makefile

@@ -339,6 +339,7 @@ install: lib xxhsum  ## install libraries, CLI, links and man page
 	@ln -sf $(LIBXXH) $(DESTDIR)$(LIBDIR)/libxxhash.$(SHARED_EXT)
 	@$(INSTALL) -d -m 755 $(DESTDIR)$(INCLUDEDIR)   # includes
 	@$(INSTALL_DATA) xxhash.h $(DESTDIR)$(INCLUDEDIR)
+	@$(INSTALL_DATA) xxh3.h $(DESTDIR)$(INCLUDEDIR)
 	@echo Installing xxhsum
 	@$(INSTALL) -d -m 755 $(DESTDIR)$(BINDIR)/ $(DESTDIR)$(MANDIR)/
 	@$(INSTALL_PROGRAM) xxhsum $(DESTDIR)$(BINDIR)/xxhsum

cmake_unofficial/CMakeLists.txt

@@ -44,7 +44,6 @@ if(NOT CMAKE_CONFIGURATION_TYPES)
 endif()
 
 option(BUILD_SHARED_LIBS "Build shared library" ON)
-set(XXHASH_BUILD_ENABLE_INLINE_API ON CACHE BOOL "add xxhash.c to includes for -DXXH_INLINE_ALL")
 set(XXHASH_BUILD_XXHSUM ON CACHE BOOL "Build the xxhsum binary")
 
 # If XXHASH is being bundled in another project, we don't want to
@@ -123,10 +122,8 @@ if(NOT XXHASH_BUNDLED_MODE)
     ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}")
   install(FILES "${XXHASH_DIR}/xxhash.h"
     DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
-  if(XXHASH_BUILD_ENABLE_INLINE_API)
-    install(FILES "${XXHASH_DIR}/xxhash.c"
-      DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
-  endif()
+  install(FILES "${XXHASH_DIR}/xxh3.h"
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
   if(XXHASH_BUILD_XXHSUM)
     install(TARGETS xxhsum
       EXPORT xxHashTargets