fix some symbol resolution issues in dynamic linker

1. search was wrongly beginning with lib itself rather than dso head
2. inconsistent resolution of function pointers for functions in plt

arch/i386/reloc.h

@@ -4,6 +4,7 @@
 #define ETC_LDSO_PATH "/etc/ld-musl-i386.path"
 
 #define IS_COPY(x) ((x)==R_386_COPY)
+#define IS_PLT(x) ((x)==R_386_JMP_SLOT)
 
 static inline void do_single_reloc(size_t *reloc_addr, int type, size_t sym_val, size_t sym_size, unsigned char *base_addr, size_t addend)
 {

arch/x86_64/reloc.h

@@ -5,6 +5,7 @@
 #define ETC_LDSO_PATH "/etc/ld-musl-x86_64.path"
 
 #define IS_COPY(x) ((x)==R_X86_64_COPY)
+#define IS_PLT(x) ((x)==R_X86_64_JUMP_SLOT)
 
 static inline void do_single_reloc(size_t *reloc_addr, int type, size_t sym_val, size_t sym_size, unsigned char *base_addr, size_t addend)
 {

src/ldso/dynlink.c

@@ -114,7 +114,7 @@ static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t
 			sym = syms + sym_index;
 			name = strings + sym->st_name;
 			ctx = IS_COPY(type) ? dso->next : dso;
-			sym_val = (size_t)find_sym(ctx, name, 1);
+			sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
 			sym_size = sym->st_size;
 		}
 		do_single_reloc(reloc_addr, type, sym_val, sym_size, base, rel[2]);
@@ -335,11 +335,11 @@ static void reloc_all(struct dso *p)
 		if (p->relocated) continue;
 		decode_vec(p->dynv, dyn, DYN_CNT);
 		do_relocs(p->base, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
-			2+(dyn[DT_PLTREL]==DT_RELA), p->syms, p->strings, p);
+			2+(dyn[DT_PLTREL]==DT_RELA), p->syms, p->strings, head);
 		do_relocs(p->base, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ],
-			2, p->syms, p->strings, p);
+			2, p->syms, p->strings, head);
 		do_relocs(p->base, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ],
-			3, p->syms, p->strings, p);
+			3, p->syms, p->strings, head);
 		p->relocated = 1;
 	}
 }