blackfin: fix undefined reference to srand and rand

Commit 9ba9e85f3f1c (net: Fix NET_RANDOM_ETHADDR dependencies)
accidentally dropped CONFIG_LIB_RAND defines for 14 Blackfin boards.

Prior to that commit, those boards defined CONFIG_LIB_RAND, but not
CONFIG_NET_RANDOM_ETHADDR.  So, commit 9ba9e85f3f1c should not have
touched them, but in fact it ripped CONFIG_LIB_RAND off from all the
header files, which caused undefined reference to srand and rand.
CONFIG_LIB_RAND=y must be revived for such boards.

BTW, this commit indeed makes it better, but even with this fix,
three boards (bf533-stamp, bf538f-ezkit, cm-bf548) still can not
build due to region 'ram' overflowed error.  This was cause by
commit 6eed3786c68c (net: Move the CMD_NET config to defconfigs)
because CMD_NET selects NET, and NET selects REGEX.  Eventually,
some boards were newly enabled with CONFIG_REGEX, increasing the
memory footprint.  A patch is expected to fix the build error.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

configs/bf527-ezkit-v2_defconfig

@@ -3,3 +3,4 @@ CONFIG_TARGET_BF527_EZKIT=y
 CONFIG_SYS_EXTRA_OPTIONS="BF527_EZKIT_REV_2_1"
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf533-ezkit_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF533_EZKIT=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf533-stamp_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF533_STAMP=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf538f-ezkit_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF538F_EZKIT=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf548-ezkit_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF548_EZKIT=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf561-acvilon_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF561_ACVILON=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf561-ezkit_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF561_EZKIT=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/bf609-ezkit_defconfig

@@ -3,3 +3,4 @@ CONFIG_NETDEVICES=y
 CONFIG_TARGET_BF609_EZKIT=y
 CONFIG_CMD_NET=y
 CONFIG_ETH_DESIGNWARE=y
+CONFIG_LIB_RAND=y

configs/br4_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_BR4=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/cm-bf533_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_CM_BF533=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/cm-bf548_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_CM_BF548=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/cm-bf561_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_CM_BF561=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

configs/ibf-dsp561_defconfig

@@ -1,3 +1,4 @@
 CONFIG_BLACKFIN=y
 CONFIG_TARGET_IBF_DSP561=y
 CONFIG_CMD_NET=y
+CONFIG_LIB_RAND=y

configs/pr1_defconfig

@@ -2,3 +2,4 @@ CONFIG_BLACKFIN=y
 CONFIG_TARGET_PR1=y
 CONFIG_CMD_NET=y
 CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED=y
+CONFIG_LIB_RAND=y

lib/Kconfig

@@ -45,7 +45,9 @@ config REGEX
 	  "setexpr".
 
 config LIB_RAND
-	bool
+	bool "Pseudo-random library support "
+	help
+	  This library provides pseudo-random number generator functions.
 
 source lib/rsa/Kconfig