[RISCV][crt] support building without init_array

Reviewed By: luismarques, phosek, kito-cheng

Differential Revision: https://reviews.llvm.org/D87997

Author: spacemonkeydelivers

compiler-rt/lib/crt/crtbegin.c

@@ -52,6 +52,10 @@ __attribute__((section(".init_array"),
 __asm__(".pushsection .init,\"ax\",@progbits\n\t"
     "call " __USER_LABEL_PREFIX__ "__do_init\n\t"
     ".popsection");
+#elif defined(__riscv)
+__asm__(".pushsection .init,\"ax\",%progbits\n\t"
+        "call " __USER_LABEL_PREFIX__ "__do_init\n\t"
+        ".popsection");
 #elif defined(__arm__) || defined(__aarch64__)
 __asm__(".pushsection .init,\"ax\",%progbits\n\t"
     "bl " __USER_LABEL_PREFIX__ "__do_init\n\t"
@@ -110,6 +114,10 @@ __asm__(".pushsection .fini,\"ax\",@progbits\n\t"
     "bl " __USER_LABEL_PREFIX__ "__do_fini\n\t"
     "nop\n\t"
     ".popsection");
+#elif defined(__riscv)
+__asm__(".pushsection .fini,\"ax\",@progbits\n\t"
+        "call " __USER_LABEL_PREFIX__ "__do_fini\n\t"
+        ".popsection");
 #elif defined(__sparc__)
 __asm__(".pushsection .fini,\"ax\",@progbits\n\t"
     "call " __USER_LABEL_PREFIX__ "__do_fini\n\t"