Add janet.h (in addition to janet/janet.h) on install.

A number of bindings (many of which I have written) include
<janet.h> rather than <janet/janet.h>.

Makefile

@@ -282,6 +282,7 @@ install: $(JANET_TARGET) $(JANET_LIBRARY) $(JANET_STATIC_LIBRARY) build/janet.pc
 	cp $(JANET_TARGET) '$(DESTDIR)$(BINDIR)/janet'
 	mkdir -p '$(DESTDIR)$(INCLUDEDIR)/janet'
 	cp -r build/janet.h '$(DESTDIR)$(INCLUDEDIR)/janet'
+	ln -sf '$(DESTDIR)$(INCLUDEDIR)/janet/janet.h' '$(DESTDIR)$(INCLUDEDIR)/janet.h'
 	mkdir -p '$(DESTDIR)$(JANET_PATH)'
 	mkdir -p '$(DESTDIR)$(LIBDIR)'
 	if test $(UNAME) = Darwin ; then \
@@ -315,6 +316,7 @@ install-jpm-git: $(JANET_TARGET)
 uninstall:
 	-rm '$(DESTDIR)$(BINDIR)/janet'
 	-rm -rf '$(DESTDIR)$(INCLUDEDIR)/janet'
+	-rm -rf '$(DESTDIR)$(INCLUDEDIR)/janet.h'
 	-rm -rf '$(DESTDIR)$(LIBDIR)'/libjanet.*
 	-rm '$(DESTDIR)$(JANET_PKG_CONFIG_PATH)/janet.pc'
 	-rm '$(DESTDIR)$(JANET_MANPATH)/janet.1'

meson.build

@@ -263,3 +263,6 @@ patched_janet = custom_target('patched-janeth',
   build_by_default : true,
   output : ['janet.h'],
   command : [janet_nativeclient, '@INPUT@', '@OUTPUT@'])
+
+# Create a version of the janet.h header that matches what jpm often expects
+install_symlink('janet.h', pointing_to: 'janet/janet.h', install_dir: get_option('includedir'))