tools: Update picolibc toolchain configuration

This change updates the multilib list to ensure compatibility with
settings used in other Caliptra repositories.

Signed-off-by: Miguel Osorio <miguelosorio@google.com>

Author: moidx

tools/picolibc.mk

@@ -43,7 +43,7 @@ $(INSTALL_PATH)/picolibc.specs: $(BUILD_PATH)/cross.txt | $(BUILD_PATH)
 
 	cd $(PICOLIBC_PATH) && meson $(BUILD_PATH) \
 		-Dmultilib=true \
-		-Dmultilib-list=rv32imac/ilp32 \
+		-Dmultilib-list=rv32imc/ilp32 \
 		-Dpicocrt=false \
 		-Datomic-ungetc=false \
 		-Dthread-local-storage=false \