Only enable lto on linux for now.

Was failing with clang, as the default clang linker doesn't
do LTO.

Makefile

@@ -37,7 +37,7 @@ MANPATH?=$(PREFIX)/share/man/man1/
 PKG_CONFIG_PATH?=$(LIBDIR)/pkgconfig
 DEBUGGER=gdb
 
-CFLAGS:=$(CFLAGS) -std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fPIC -O2 -fvisibility=hidden -flto \
+CFLAGS:=$(CFLAGS) -std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fPIC -O2 -fvisibility=hidden \
 	   -DJANET_BUILD=$(JANET_BUILD)
 LDFLAGS=-rdynamic
 
@@ -51,6 +51,7 @@ ifeq ($(UNAME), Darwin)
 	LDCONFIG:=
 else ifeq ($(UNAME), Linux)
 	CLIBS:=$(CLIBS) -lrt -ldl
+	CFLAGS+= -flto
 endif
 # For other unix likes, add flags here!
 ifeq ($(UNAME), Haiku)

auxbin/jpm

@@ -125,11 +125,11 @@
 (def threads? (not (not (env 'thread/new))))
 
 # Default flags for natives, but not required
-(def default-lflags (if is-win ["/nologo"] ["-flto"]))
+(def default-lflags (if is-win ["/nologo"] []))
 (def default-cflags
   (if is-win
     ["/nologo" "/MD"]
-    ["-std=c99" "-Wall" "-Wextra" "-flto"]))
+    ["-std=c99" "-Wall" "-Wextra"]))
 
 
 # Link to pthreads
@@ -140,13 +140,13 @@
 (def- dynamic-cflags
   (if is-win
     ["/LD"]
-    ["-fPIC" "-flto"]))
+    ["-fPIC"]))
 (def- dynamic-lflags
     (if is-win
       ["/DLL" ;thread-flags]
       (if is-mac
-        ["-shared" "-undefined" "dynamic_lookup" "-flto" ;thread-flags]
-        ["-shared" "-flto" ;thread-flags])))
+        ["-shared" "-undefined" "dynamic_lookup" ;thread-flags]
+        ["-shared" ;thread-flags])))
 
 (defn- opt
   "Get an option, allowing overrides via dynamic bindings AND some