orage uses a symbol from libX11, but doesn't link directly to it. It should do so. 

See: https://fedoraproject.org/wiki/Features/ChangeInImplicitDSOLinking
for more info. 

/usr/bin/ld: orage-main.o: undefined reference to symbol 'XGetSelectionOwner'
/usr/bin/ld: note: 'XGetSelectionOwner' is defined in DSO /usr/lib64/libX11.so.6 so try adding it to the linker command line
/usr/bin/ld: globaltime-globaltime.o: undefined reference to symbol 'XGetSelectionOwner'
/usr/bin/ld: note: 'XGetSelectionOwner' is defined in DSO /usr/lib64/libX11.so.6 so try adding it to the linker command line
/usr/bin/ld: orage-ical-code.o: undefined reference to symbol 'floor@@GLIBC_2.2.5'
/usr/bin/ld: note: 'floor@@GLIBC_2.2.5' is defined in DSO /lib64/libm.so.6 so try adding it to the linker command line

Hacky patch (you'll want to add it more correctly to the automake files): 

diff -Nur orage-4.6.1.orig/globaltime/Makefile.in orage-4.6.1/globaltime/Makefile.in
--- orage-4.6.1.orig/globaltime/Makefile.in	2009-04-14 16:59:40.000000000 -0600
+++ orage-4.6.1/globaltime/Makefile.in	2010-02-14 00:39:38.000000000 -0700
@@ -145,7 +145,7 @@
 INTLTOOL_XML_NOMERGE_RULE = @INTLTOOL_XML_NOMERGE_RULE@
 INTLTOOL_XML_RULE = @INTLTOOL_XML_RULE@
 LD = @LD@
-LDFLAGS = @LDFLAGS@
+LDFLAGS = @LDFLAGS@ -lX11
 LEX = @LEX@
 LEXLIB = @LEXLIB@
 LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@
diff -Nur orage-4.6.1.orig/panel-plugin/Makefile.in orage-4.6.1/panel-plugin/Makefile.in
--- orage-4.6.1.orig/panel-plugin/Makefile.in	2009-04-14 16:59:44.000000000 -0600
+++ orage-4.6.1/panel-plugin/Makefile.in	2010-02-14 00:18:49.000000000 -0700
@@ -154,7 +154,7 @@
 INTLTOOL_XML_NOMERGE_RULE = @INTLTOOL_XML_NOMERGE_RULE@
 INTLTOOL_XML_RULE = @INTLTOOL_XML_RULE@
 LD = @LD@
-LDFLAGS = @LDFLAGS@
+LDFLAGS = @LDFLAGS@ -lX11
 LEX = @LEX@
 LEXLIB = @LEXLIB@
 LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@
diff -Nur orage-4.6.1.orig/src/Makefile.in orage-4.6.1/src/Makefile.in
--- orage-4.6.1.orig/src/Makefile.in	2009-04-14 16:59:45.000000000 -0600
+++ orage-4.6.1/src/Makefile.in	2010-02-13 23:57:08.000000000 -0700
@@ -186,7 +186,7 @@
 INTLTOOL_XML_NOMERGE_RULE = @INTLTOOL_XML_NOMERGE_RULE@
 INTLTOOL_XML_RULE = @INTLTOOL_XML_RULE@
 LD = @LD@
-LDFLAGS = @LDFLAGS@
+LDFLAGS = @LDFLAGS@ -lX11 -lm
 LEX = @LEX@
 LEXLIB = @LEXLIB@
 LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@