Change pthreads linking with jpm, make, and meson.

Try to add pthread deps when compiling programs with jpm.

Makefile

@@ -28,7 +28,7 @@ INCLUDEDIR?=$(PREFIX)/include
 BINDIR?=$(PREFIX)/bin
 LIBDIR?=$(PREFIX)/lib
 JANET_BUILD?="\"$(shell git log --pretty=format:'%h' -n 1)\""
-CLIBS=-lm
+CLIBS=-lm -lpthread
 JANET_TARGET=build/janet
 JANET_LIBRARY=build/libjanet.so
 JANET_STATIC_LIBRARY=build/libjanet.a
@@ -37,7 +37,7 @@ MANPATH?=$(PREFIX)/share/man/man1/
 PKG_CONFIG_PATH?=$(LIBDIR)/pkgconfig
 DEBUGGER=gdb
 
-CFLAGS=-std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fPIC -O2 -fvisibility=hidden -pthread \
+CFLAGS=-std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fPIC -O2 -fvisibility=hidden \
 	   -DJANET_BUILD=$(JANET_BUILD)
 LDFLAGS=-rdynamic
 

auxbin/jpm

@@ -112,6 +112,10 @@
 (def default-linker (if is-win "link" "cc"))
 (def default-archiver (if is-win "lib" "ar"))
 
+# Detect threads
+(def env (fiber/getenv (fiber/current)))
+(def threads? (not (not (env 'threads/from-image))))
+
 # Default flags for natives, but not required
 (def default-lflags (if is-win ["/nologo"] []))
 (def default-cflags
@@ -119,6 +123,10 @@
     ["/nologo" "/MD"]
     ["-std=c99" "-Wall" "-Wextra"]))
 
+
+# Link to pthreads
+(def- thread-flags (if is-win [] (if threads? ["-lpthread"] [])))
+
 # Required flags for dynamic libraries. These
 # are used no matter what for dynamic libraries.
 (def- dynamic-cflags
@@ -127,10 +135,10 @@
     ["-fPIC"]))
 (def- dynamic-lflags
     (if is-win
-      ["/DLL"]
+      ["/DLL" ;thread-flags]
       (if is-mac
-        ["-shared" "-undefined" "dynamic_lookup"]
-        ["-shared"])))
+        ["-shared" "-undefined" "dynamic_lookup" ;thread-flags]
+        ["-shared" ;thread-flags])))
 
 (defn- opt
   "Get an option, allowing overrides via dynamic bindings AND some

meson.build

@@ -30,6 +30,7 @@ header_path = join_paths(get_option('prefix'), get_option('includedir'), 'janet'
 cc = meson.get_compiler('c')
 m_dep = cc.find_library('m', required : false)
 dl_dep = cc.find_library('dl', required : false)
+thread_dep = dependency('threads')
 
 # Link options
 if build_machine.system() != 'windows'
@@ -156,7 +157,7 @@ mainclient_src = [
 janet_boot = executable('janet-boot', core_src, boot_src, boot_gen,
   include_directories : incdir,
   c_args : '-DJANET_BOOTSTRAP',
-  dependencies : [m_dep, dl_dep],
+  dependencies : [m_dep, dl_dep, thread_dep],
   native : true)
 
 # Build core image
@@ -167,7 +168,7 @@ core_image = custom_target('core_image',
 
 libjanet = library('janet', core_src, core_image,
   include_directories : incdir,
-  dependencies : [m_dep, dl_dep],
+  dependencies : [m_dep, dl_dep, thread_dep],
   install : true)
 
 # Extra c flags - adding -fvisibility=hidden matches the Makefile and
@@ -187,14 +188,14 @@ endif
 
 janet_mainclient = executable('janet', core_src, core_image, mainclient_src,
   include_directories : incdir,
-  dependencies : [m_dep, dl_dep],
+  dependencies : [m_dep, dl_dep, thread_dep],
   c_args : extra_native_cflags,
   install : true)
 
 if meson.is_cross_build()
   janet_nativeclient = executable('janet-native', core_src, core_image, mainclient_src,
     include_directories : incdir,
-    dependencies : [m_dep, dl_dep],
+    dependencies : [m_dep, dl_dep, thread_dep],
     c_args : extra_cross_cflags,
     native : true)
 else
@@ -224,7 +225,7 @@ amalg_shell = custom_target('amalg-shell',
 # Amalgamated client
 janet_amalgclient = executable('janet-amalg', amalg, amalg_shell,
   include_directories : incdir,
-  dependencies : [m_dep, dl_dep],
+  dependencies : [m_dep, dl_dep, thread_dep],
   build_by_default : false)
 
 # Tests