Fix freertos_kernel cmake property, Posix Port (#640)

* Fix freertos_kernel cmake property, Posix Port

* Moves the `set_property()` call below the target definition in top level CMakeLists file
* Corrects billion value from `ULL` suffix (not C90 compliant) to `UL` suffix with cast to uint64_t

* Add blank line to CMakeLists.txt
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b51b7aa..6d83db8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -229,10 +229,6 @@
 endif()
 
 ########################################################################
-# Requirements
-set_property(TARGET freertos_kernel PROPERTY C_STANDARD 90)
-
-########################################################################
 # Overall Compile Options
 # Note the compile option strategy is to error on everything and then
 # Per library opt-out of things that are warnings/errors.
@@ -294,3 +290,7 @@
         $<$<TARGET_EXISTS:freertos_config>:freertos_config>
         freertos_kernel_port
 )
+
+########################################################################
+# Requirements
+set_property(TARGET freertos_kernel PROPERTY C_STANDARD 90)
diff --git a/portable/ThirdParty/GCC/Posix/port.c b/portable/ThirdParty/GCC/Posix/port.c
index 12076b9..d634c8b 100644
--- a/portable/ThirdParty/GCC/Posix/port.c
+++ b/portable/ThirdParty/GCC/Posix/port.c
@@ -343,7 +343,7 @@
 
     clock_gettime( CLOCK_MONOTONIC, &t );
 
-    return ( uint64_t )t.tv_sec * 1000000000ULL + ( uint64_t )t.tv_nsec;
+    return ( uint64_t )t.tv_sec * ( uint64_t )1000000000UL + ( uint64_t )t.tv_nsec;
 }
 
 static uint64_t prvStartTimeNs;