samples/basic/minimal: make it smaller

Add a config entry specifically for RISC-V runtime.
Memory usage is 7066 bytes.

Also adjust some library options. This make the ARC runtime binary
smaller as well:

before:

        FLASH:        8808 B
         SRAM:        3672 B

after:

        FLASH:        5596 B
         SRAM:        3672 B

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>

samples/basic/minimal/common-runtime.conf

@@ -5,6 +5,19 @@ CONFIG_GPIO=n
 CONFIG_PINCTRL=n
 CONFIG_SPI=n
 CONFIG_FLASH=n
+CONFIG_UART_USE_RUNTIME_CONFIGURE=n
+CONFIG_UART_INTERRUPT_DRIVEN=n
+
+# libs
+CONFIG_MINIMAL_LIBC=y
+CONFIG_CBPRINTF_NANO=y
+CONFIG_CBPRINTF_REDUCED_INTEGRAL=y
+CONFIG_CBPRINTF_LIBC_SUBSTS=n
+
+# build
+CONFIG_FPU=n
+CONFIG_SIZE_OPTIMIZATIONS=y
 
 # Boot
 CONFIG_BOOT_DELAY=0
+CONFIG_SAMPLE_DO_OUTPUT=y

samples/basic/minimal/riscv.conf

@@ -0,0 +1 @@
+CONFIG_RISCV_PMP=n

samples/basic/minimal/sample.yaml

@@ -3,6 +3,11 @@ sample:
   name: minimal
 common:
   tags: footprint
+  harness: console
+  harness_config:
+    type: one_line
+    regex:
+      - "Hello World from minimal!"
 tests:
   sample.minimal.mt.arm:
     extra_args: CONF_FILE='common.conf;mt.conf;arm.conf'
@@ -76,17 +81,19 @@ tests:
     extra_args: CONF_FILE='common.conf;no-mt.conf;no-timers.conf;x86.conf'
     build_only: true
     platform_allow: qemu_x86
-  sample.minimal.no-timers.runtime:
+  sample.minimal.arc.runtime:
     extra_args:
       - CONF_FILE='common-runtime.conf;no-timers.conf'
-      - CONFIG_SAMPLE_DO_OUTPUT=y
     arch_allow: arc
     tags:
       - kernel
     integration_platforms:
       - qemu_arc_em
-    harness: console
-    harness_config:
-      type: one_line
-      regex:
-        - "Hello World from minimal!"
+  sample.minimal.riscv.runtime:
+    extra_args:
+      - CONF_FILE='common-runtime.conf;no-timers.conf;no-mt.conf;riscv.conf'
+    platform_allow: qemu_riscv32
+    tags:
+      - kernel
+    integration_platforms:
+      - qemu_riscv32